Abstract
Study objectives
The International Classification of Sleep Disorders categorized catathrenia as a respiratory disorder, but there are doubts whether episodes appear during rapid eye movement (REM) sleep or the non-rapid eye movement (NREM), their duration, and symptoms. The main objectives were to identify the most common features and relations of catathrenia.
Methods
PubMed, Embase, and Web of Science were searched according to the PRISMA 2020 guidelines. The Joanna Briggs Institute and the ROBINS-I tools were chosen to assess the risk of bias.
Results
A total of 288 records were identified, 31 articles were included. The majority of the studies had a moderate risk of bias. 49.57% of episodes occurred during the NREM sleep, while 46% took place during REM. In 60.34% females, catathrenia was more common in the NREM, while in 59.26% of males was in REM sleep (p < 0.05). Females and obese individuals were found to have shorter episodes (p < 0.05). Age was inversely correlated with minimal episodes duration (r = − 0.34). The continuous positive airway pressure (CPAP) therapy was inversely correlated with the maximal episode duration (r = − 0.48).
Conclusions
Catathrenia occurs with similar frequency in both genders. The most frequent symptoms embraced groaning, awareness of disturbing bedpartners, and daytime somnolence—not confirmed by the Epworth Sleepiness Scale. The episodes occur more frequently in NREM than in REM sleep. Catathrenia may be considered as a sex-specific condition. The effects of CPAP treatment leading to shortening episodes duration, which may indicate the respiratory origin of catathrenia.
Similar content being viewed by others
Avoid common mistakes on your manuscript.
Introduction
Sleep disorders affect millions of people in the USA [1]. These problems can occur in up to 41% of young adult females and 42.3% of males [2]. Sleep disturbances are connected with serious diseases such as depression, dementia, strokes, migraine, and hypertension [3,4,5,6,7], and may subsequently increase the mortality rate among patients experiences these disorders [1, 8, 9]. Although insufficient awareness of sleep disorders exists in the general population [10], the symptoms of sleep problems, e.g., excessive daytime sleepiness, snoring, chronic fatigue, or impaired daytime functioning [11,12,13,14] have led to an increased number of doctor’s appointments. Subsequently there is observed a rise in the number of patients being diagnosed with sleep disorders [15]. However, atypical symptoms such as nocturnal groaning without awareness, as observed in catathrenia, could remain undiagnosed for many years [16]. Only when family or bed partners observe and complain of disturbing sounds during sleep, sleep evaluation will be finally conducted [17].
Catathrenia is characterized by the production of nocturnal groaning or moaning during expiration [18]. The sound of catathrenia is described as having rhythmic or semi-rhythmic formants that arise in the vocal cords. This is in contrast to a similar sound produced during snoring, which has instead been described as a sound with a guttural chaotic waveform that is produced both during inspiration and expiration [19, 20]. The differential diagnosis of nocturnal sounds includes sleep apneas, snoring, laryngospasm, stridor, and somniloquy (sleep talking) [21]. The global prevalence of catathrenia is unknown. However, it has been suggested that the problem involves approximately 0.063 to 0.54% of patients that have been referred to sleep specialists [19]. The name “catathrenia” itself was only established in 2001. The origin of the word “cathrenia” is Greek, with “threnia” meaning “to lament,” and “kata” meaning “below” [22]. One of the reasons for catathrenia being described so rarely in literature may be caused by closely resembles of sleep apnea and nocturnal moaning in polysomnography (PSG) recordings. These are difficult to differentiate, particularly when they are examined by inexperienced persons who do not have access to audio and video recordings [16]. Additionally, cases of catathrenia are also identified accidentally while screening for a sleep breathing disorder [23].
There is a significant amount of inconsistent data on the topic of catathrenia. First of all, catathrenia was initially classified by the International Classification of Sleep Disorders (ICD-2) as rapid eye movement (REM) related parasomnia. However, in the third edition of this classification (ISCD-3), it has been classified as a respiratory disorder [24]. In ISCD-3, catathrenia has been described as occurring predominantly during REM sleep. However, studies have emerged reporting episodes of catathrenia that occurred predominantly, or even only, during the NREM sleep [25,26,27]. Reported symptoms are also inconclusive, as some patients do not report any morning complaints [22, 27, 28], while some only report mild hoarseness [29]. Others however have reported symptoms that have severely affected their lives, such as excessive daytime sleepiness, unrefreshing sleep, choking episodes, and a decreased ability to concentrate during the day [16, 21]. The duration of the groaning sounds is in the range of 2–49 s according to ISCD-2 [30]. However, some studies in literature have described episodes as short as 0.4 s or as long as 154 s [25, 31, 32]. Several authors have reported the potential association between catathrenia and obstructive sleep apnea (OSA) [16, 33, 34]; however, still little is known about potential predisposing comorbid diseases for catathrenia [18].
This systematic review was performed to analyze the studies investigating catathrenia and to aggregate the existing data for a better understanding of this condition. The primary objective was to identify the most common features of catathrenia. The second objective was to determine the potential association between catathrenia and other diseases, gender, symptoms, or particular sleep stages.
Methods
Our systematic review was conducted according to the criteria established by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 (PRISMA 2020). This systematic review was not registered.
Eligibility criteria
Inclusion criteria included single cases such as case reports and case series or cohort, cross-sectional, case–control, or descriptive studies where the detailed descriptions of patients experienced catathrenia were presented. This review took into consideration patients age, gender, symptoms, and the method in which this condition was diagnosed. No time constraint was placed on the publication date of the analyzed studies; however, the studies had to be written in English and were required to have full-text availability. Exclusion criteria were as follows: subjects unrelated to our topic; non-English articles; non-original records such as reviews, book chapters, letters to the editor and comments; papers that did not describe features of catathrenia; records containing the new catathrenia description, that could not be appropriately assessed for risk of bias; studies that could not be retrieved for evaluation.
Information sources and searching strategy
In order to identify articles related to this systemic review, three medical databases were searched on May 5, 2023: PubMed, Embase and Web of Science. The following key terms were used to browse the databases: “catathrenia” OR “nocturnal groaning” OR “sleep-related groaning” OR “expiratory groaning” OR “nocturnal moaning” OR “nocturnal vocalization.” The initial search did not use any filters. Initially, the overall number of records were identified by two authors (BB and HM). Then, based on data obtained from the title and abstract, the duplicates, non-English studies, and papers unrelated to catathrenia were excluded. Next, full-text records were read by two authors (BB and HM) separately, who extracted the data and later compared the results. According to the eligibility criteria mentioned in the “Eligibility criteria” section, as well as the PRISMA 2020 guidelines, BB and HM excluded papers to reach studies that had focused on describing the catathrenia condition alone. If two authors (BB and HM) were in conflict during the inclusion process, the third author (MW) resolved this problem by means of a discussion.
Data extraction
The following data was extracted from the included studies: the authors, type of study, number of patients, their gender, age, reported symptoms, their comorbidities, concomitant sleep disorders, points obtained in the Epworth Sleepiness Scale (ESS), methods used to diagnose catathrenia, the sleep stage in which the episode of moaning occurred, moaning duration, frequency of nocturnal episodes, groaning vocalization, and methods used to treat catathrenia. The extraction of the data was conducted independently by two authors (BB and HM).
Risk of bias evaluation
Due to a large variety of included studies such as case reports, case series, cohort studies, and case–control studies, multi-adjustment tools had to be utilized. The Joanna Briggs Institute (JBI) critical appraisal tools were used for case reports and case series [35]. Non-randomized observational studies such as cohort and case–control studies however were analyzed with the ROBINS-I tool [36]. The possible answers to JBI questions were “yes,” “no,” “unclear,” and “not applicable.” The overall risk of bias could be low, moderate, or high. According to the JBI checklists, case reports were analyzed on the basis of 8 questions, while case series were analyzed using 10 questions. To be classified as having a low risk of bias, case reports had to receive at least 7 “yes” answers, while 9 “yes” responses were expected in the case series and cohort articles. For a study to be deemed as having a high risk of bias, a case report had to receive less than 5 “yes” answers, while case series papers had to receive less than 6 positive responses. Papers were considered to have a moderate risk of bias when answers were found to be between the abovementioned ranges. Using ROBINS-I, 7 domains of potential bias were determined. Judgements in each of the domains, as well as overall assessment, could be assigned as “low,” “moderate,” “serious,” or at “critical” risk of bias. A study was considered to have an overall low risk of bias in ROBINS-I if all domains were deemed to be at “low risk.” A “moderate risk” of bias was considered if a particular study had obtained either low or moderate risk responses in 7 domains. An overall “serious” or “critical risk” of bias was assigned when a particular study had received either of these categories in at least one domain. Evaluation for the risk of bias was assessed separately by two authors (BB and HM) who had compared the data.
Statistical analysis
To reach the primary objective of our systematic review, extracted data was analyzed using Statistica 13.3 (Statsoft, Poland). Data is presented as a mean and standard deviation (SD), in some cases as weighted arithmetic mean and weighted SD. Data was analyzed using the Spearman rank correlation coefficient and chi-square χ2. The differences between two groups were analyzed with the non-parametric Mann–Whitney U test. For all analysis, p < 0.05 was considered to be statistically significant. Because of heterogenous characteristics being analyzed across the various studies, the number of variables (n) for each analysis can differ. The missing data was deleted pairwise and each result of the analysis is supported by the number of variables (n).
Results
Included studies
After searching the key terms in three databases, we identified a total of 288 records: 67 in PubMed, 123 in Embase, and 98 in Web of Science. Next, 146 duplicates were removed. Following this 10 non-English papers, 11 papers unrelated to catathrenia and 3 records without full access were removed after the assessment of the title or abstract. Then, for the eligibility process, 118 full-text papers were read. According to the criteria laid out in Sect. "Eligibility criteria" and in accordance with PRISMA 2020 guidelines, 53 conference abstracts, 14 reviews, 4 letters to the editor, 2 book chapters, 8 comments, and 6 papers not fitting to any standard type of article, were excluded from the final analysis. Finally, 31 papers [16,17,18,19, 22, 25,26,27,28, 30,31,32,33, 37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54] had met the criteria of our study and were included in the review. The detailed steps of the study selection are presented in Fig. 1.
Study characteristics
Thirty-one articles [16,17,18,19, 22, 25,26,27,28, 30,31,32,33, 37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54] were included for further analysis. These included 6 cohort studies [16, 26, 31, 42,43,44], 1 case–control study [39], 10 case series [19, 22, 24, 25, 37, 38, 40, 41, 45, 47], and 14 case reports [17, 18, 27, 28, 30, 32, 33, 46, 49,50,51,52,53,54]. However, in 3 studies [16, 25, 43], data was reported with SD and mean values. These were therefore excluded from further analysis. Without these 3 studies, the group of participants consisted of 127 patients, where there was a slight predominance of female (n = 69) over male patients (n = 58). The average age was 31.45 ± 14.66 years old. Unfortunately, as the studies were not homogenous in nature and different characteristics were evaluated across the papers, some studies did not contain the analyzed values that we mentioned; thus, our review always reports on the number of patients (n) who were included in the analysis of a particular feature. The overall body mass index (BMI) for all participants was 24.20 ± 5.73 kg/m2 (n = 76), with 13.16% of them being categorized as obese. These data are presented in Table 1. But all features of the included studies have been extensively shown in supplementary materials in Table 1.
Clinical features of catathrenia
Based on data obtained from the studies, we determined that catathrenia episodes occurred in 47.86% ± 30.46% in NREM sleep and 51.31% ± 31.16% in REM sleep (n = 91; Fig. 2). 6.10% of nocturnal groaning episodes were observed during awakenings from sleep (n = 10). In the assessment of the phase of sleep in which these episodes dominated, we found that in 49.57% cases episodes of catathrenia were more frequent in the NREM sleep, while 46% of cases they occurred more frequently in the REM cycle (n = 117). The minimal duration of episodes was determined to be 2.22 ± 3.81 s, while the maximal duration of the episodes was 43.04 ± 28.51 s (n = 71; Fig. 3). Forty-two out of 96 patients reported awareness about occurring episodes at their home, whereas 30 of them complained of episodes occurring every night. The precise vocalization of catathrenia was evaluated in only 50 patients. The most common type of analyzed vocalization during hospital examination was the type I sound with a sinusoidal waveform. The second was the type II sound with a semi-rhythmic sawtooth waveform.
The most frequently reported complaints included awareness of disturbing to bed partners, snoring, groaning, atypical nocturnal sounds, abnormal patterns of sleep breathing, and excessive daytime sleepiness (EDS) (n = 92). The EDS was estimated by the Epworth Sleepiness Scale (ESS). Mean ESS score was 5.78 ± 4.65 points (n = 107). Other frequently described complaints included nocturnal noises, family concerns about their health and the sensation of a dry mouth in the morning. Studies that focused on health concerns, determined that 46.58% of participants were healthy (n = 73). While focusing on concomitant sleep disorders, almost 20% of participants did not demonstrate any other sleep disorders. Of the remaining patients, 11.30% had insomnia, followed by less frequently occurring OSA and sleep bruxism (n = 115). It is worth noting though, that in almost 10% of the examined participants, other sleep diseases were not reported. To diagnose catathrenia, PSG was used in 122 patients. Abovementioned features of catathrenia are presented in Table 2. Treatment primarily involved CPAP therapy.
Relationship between catathrenia and gender, obesity, health status, and excessive daytime sleepiness
We assessed the potential association between gender, health status, obesity, EDS, and particular features of catathrenia such as their predominance in REM vs NREM sleep; minimum and maximum duration of episodes; and ESS score and number of reported occurring episodes at patients’ home per week. Catathrenia occurred in 46% of male and 54% of female participants. Therefore, there is no significant difference in catathrenia prevalence between the genders. However, a significant statistical difference (p < 0.05) in episodes of catathrenia between the genders was determined when analyzing their frequency of appearance in different stages of sleep (NREM vs. REM) and their minimal duration. In 60.34% females, catathrenia was more common in the NREM stage of sleep, while 59.26% male the dominant stage of sleep for catathrenia was REM sleep (n = 112, chi-square χ2 = 4.30, df = 1, p < 0.05; Fig. 4) The minimal duration of episodes was found to be significantly shorter in the female population (2.19 ± 4.87 s vs 2.25 ± 2.22 s, p < 0.05). In obese patients, catathrenia occurred more frequently during the NREM than the REM sleep. This was also statistically significant (p < 0.05). On the other hand, patients with BMI normal range (18.5–24.9 kg/m2) had episodes occurring more frequently during the REM sleep (n = 7 obese vs n = 84 non-obese). Obese participants had a significantly shorter duration of the minimal and maximal episodes duration in comparison to non-obese patients (minimal duration of episode: 0.71 ± 0.61 s vs 2.41 ± 4.00 s; maximal duration of episode: 26.51 ± 19.94 s vs 45.14 ± 28.87 s; p < 0.05). Comorbid diseases (except sleep disorders) appeared to have the greatest impact on groaning mainly during NREM sleep (n = 22 with comorbidities vs. n = 22 without them). Patients with comorbidities were also found to have on average, a shorter minimal and maximal duration of each episode (n = 29 without comorbidities vs n = 11 with them; minimal duration of episode: 2.76 ± 5.48 s vs 2.54 ± 2.50 s; maximal duration of episode: 63.59 ± 29.70 s vs 47.79 ± 21.74 s; p < 0.05) and were found to be less sleepy according to the points in the ESS scale, than healthy patients (n = 8 without comorbidities vs n = 28 with them; 6.07 ± 3.97 s vs 2.21 ± 3.41 s; p < 0.05). Additionally, patients who had abnormal ESS (above 10 points, which indicate EDS) were found to have a lower minimal duration of catathrenia episodes (1.44 ± 1.01 s vs 0.73 ± 0.44 s; p < 0.05, n = 42 ESS below 10 points vs. n = 9 ESS above 10 points). These data are shown in Table 3.
Additional correlations
Using Pearson’s correlation coefficient (r), additional associations were identified. Age was inversely correlated with the minimal duration of episodes (r = − 0.34, p < 0.05). Symptoms such as abnormal patterns of sleep breathing, as well as the sensation of a dry mouth in the morning, correlated with NREM (r = 0.74, r = 0.57, p < 0.05). Moaning episodes inversely correlated with the REM sleep (r = − 0.30, p < 0.05). The maximum duration of catathrenia episodes inversely correlated with the groaning episodes (r = − 0.29) and CPAP therapy (r = − 0.48). The minimal episode duration was also inversely correlated (r = − 0.48, r = − 0.65) with symptoms such as abnormal patterns of sleep breathing and snoring. Sleep bruxism positively correlated with the maximum duration of episodes (r = 0.26, p < 0.05). Insomnia also positively correlated with symptom groaning (r = 0.49, p < 0.05). Frequency of episodes at patients’ home, including those episodes reported every night at home, was positively correlated with the duration of REM sleep (r = 0.61, r = 0.38, p < 0.05). During CPAP therapy, catathrenia episodes correlated with the duration of NREM sleep (r = 0.69, p < 0.05).
Risk of bias
The majority of the reviewed studies were case reports. Unfortunately, 9 of the 14 case reports were determined to have a high risk of bias [17, 27, 28, 30, 32, 46, 50, 51]. Only one study in this group [49] was determined to have a low risk of bias. The remaining case reports [18, 33, 53, 54] were determined to have a moderate risk of bias. Similarly, the majority of the case series publications (6 out of 10) was deemed to have a high risk of bias [22, 24, 37, 40, 45, 47]. The remaining 4 papers had an overall moderate risk of bias [19, 25, 38, 41]. Unfortunately, not a single case series was deemed to have a low risk of bias. Using the ROBINS-I tool, 6 cohorts [16, 26, 31, 42,43,44] and 1 case–control study [39] were inspected. One study was found to have a serious risk of bias [16]. And only 1 study [43] was determined to have a low risk of bias according the ROBIN-I criteria. The rest of the studies (5 out of 7) were determined to have a moderate risk of bias [26, 31, 39, 42, 44]. Detailed descriptions for the risk of bias assessment have been presented in Table 4 for case reports, Table 5 for case series, and Table 6 for observational (cohort and case–control) studies.
Discussion
Our systematic review set out to organize existing data on catathrenia, to help us better understand this disorder. The primary objective was to identify the most common features of catathrenia. The second objective was to determine the potential association between catathrenia and gender, symptoms, and particular sleep stages. The majority of the included studies was made up of case reports and case series. Nevertheless, some conclusions can be drawn.
First of all, catathrenia was reported in a wide range of age, e.g., in the pediatric group of patients (in 4, 10, or 12 years old) [23, 28, 50, 52] or in elderly participants (including in 76-year-old patients), or mean age range of 47.9 ± 15.1 years [24, 31, 44]. The mean age of patients included in this systemic review was determined to be 31.45 ± 14.66 years. However, it is important to note that this is the calculated age at which the diagnostic process was conducted. It does not describe the mean age of atypical symptom onset, which could appear many years before the diagnosis was finally made [19, 50]. According to the ICSD-2 classification, the onset of nocturnal moaning was estimated to appear in childhood on average 9 ± 10 years [24]. Increasing age was found to be associated with a reduction in the minimum duration of these episodes; however, this was determined to be a weak correlation. Aging is often described as a risk factor for diseases such as cardiovascular disease or obesity [55, 56]; thus, we would expect that age would lengthen the duration of the episodes or in the very least have an additional negative influence on features of catathrenia. However, age seems to be a mitigating factor in this condition. It is also possible that with higher age sleep is easily disrupted by episodes of catathrenia which results in awakenings or arousals shortening the duration of episodes.
Previously, it was estimated that episodes of catathrenia would last around 2–49 s; however, our literature review uncovered that there have been episodes recorded which have either a much longer duration [32] or shorter than expected duration [28]. Our review determined that the minimal duration can be estimated to be around 2.22 ± 3.81 s, while the maximal duration was recorded to be around 43.04 ± 28.51 s, which is close to the range indicated in ICSD-2 [57].
As previously there was reported [16] that gender does not influence catathrenia and our analysis confirmed this. When considering the prevalence of groaning in particular phases of sleep, some of the reviewed studies indicated that catathrenia appeared predominantly during the REM sleep [37,38,39,40, 42]. It is worth mentioning that catathrenia was originally classified as REM parasomnia [57]. However, in literature, we could find data describing groaning episodes during the NREM sleep, while other articles even reported episodes only during NREM sleep [19, 26, 31]. Therefore, Abbasi et al. [31] divided the nocturnal episodes into two main subtypes, e.g., typical moaning, which met the ICSD-2 criteria of these episodes appearing during REM vs. atypical groaning, which dominated the NREM phase of sleep. In fact, our review found that episodes of catathrenia appeared more frequently during the NREM rather than during the REM sleep (49.57% of episodes in NREM sleep vs 46% of episodes in REM sleep). Furthermore, the incidence of catathrenia episodes in REM or in NREM sleep was different among genders. Catathrenia appeared more frequently during the NREM stage of sleep in females, while it was found to dominate the REM sleep in male participants. These relationships have thus far never been mentioned in literature. However, we have to question, whether these differences are clinically significant. If we take into account that females were determined to have a shorter minimal duration of episodes than men, we may consider catathrenia as a sex-specific condition. Overall, the prevalence of sleep disorders is greater in the female, than in the male population [58, 59], although this prevalence cannot be deemed to be significant. Nevertheless, the clinical picture suggests that females have more correlations with features of groaning. These variations however require further research.
Until recently, catathrenia was considered to be a condition with several potential mechanisms; however, it has yet to be linked to specific diseases. It was also believed to have only caused significant symptoms [16, 25]. Nocturnal groaning has sometimes been associated with sleep bruxism (SB) or OSA [25, 33, 49]. Hao et al. [60] however did find that groaning patients had completely different anatomical characteristics compared to patients with OSA, e.g., these patients were found to have a wide upper airway and large skeleton. We only found a weak relationship between SB and a prolonged maximal episode duration. Interestingly, among sleep disorders, neither OSA nor SB occurred concomitantly with catathrenia as frequently as insomnia did in our review. More intensified groaning episodes were observed in patients experienced insomnia, although this correlation was deemed to be moderate and difficult to explain. Insomnia reduces the amount of sleep and catathrenia occurs during sleep without awareness. Insomnia shorts overall periods of sleep, thus comorbid catathrenia had to have intensified episodes to would have observed catathrenia and this relationship in patients. However, the majority of patients with catathrenia did not have any other sleep problems. In comparison to OSA, Buyse et al. [61] recently discovered that catathrenia episode before severe OSA episode may slow the oxygen desaturation drop and additionally, catathrenia arousals were connected with “rescue” breathing after OSA episode. Usually in typic catathrenia, arousals after the groaning incidence were observed independently [43]. It seems that catathrenia does not change the sleep structure in contrast to OSA [62]. However, during PSG, catathrenia may imitate the central sleep apnea [16, 17] and this may be the cause of rare reporting catathrenia. There is a need to conduct further studies about the exact relationship between catathrenia and sleep apnea.
Aside from sleep disorders, we also focused on the association between catathrenia and systemic diseases; however, no such relationship was uncovered. It is worth emphasizing though that only 46.58% of participants were without comorbidities and the rest of them had comorbidities. In literature, catathrenia has been described as a condition in serious diseases such as fatal insomnia [44], Pitt–Hopkins syndrome [52], or mental retardation [37]. In our analysis, we determined that the majority of the comorbidities was made up of general disorders, such as allergic rhinitis, depression, attention-deficit hyperactivity disorder (ADHD), or obesity [16, 37, 45]. Our review also determined that comorbidities (excluding sleep disorders) played a role in the presentation of groaning during the NREM sleep; they shortened the minimal and maximal episode duration and scored less points in ESS. However, we were unable to specify which comorbidities influenced these results. Obesity was found to be a predisposing factor in the appearance of moaning during the NREM sleep and resulted in shorter episode durations. Similar to aging, obesity is also responsible for health deterioration and leads to chronic diseases and increased mortality [63]. Interestingly, though obesity was found to reduce the minimal episode duration. We do not know why the above conditions had an inverse effect on certain features of catathrenia, in contrast to other disorders. These results have not been presented in literature; therefore, to determine the association between catathrenia and health status, further studies have to be conducted.
Our study also investigated numerous symptoms reported in patients diagnosed with catathrenia. The most frequently reported complaints included awareness of disturbing to bed partners, snoring, groaning, atypical nocturnal sounds, and EDS. However, according to the ESS, which is considered to be a reliable scale used in the diagnosis of excessive sleepiness [64], albeit subjective, there were 5.78 ± 4.65 points in ESS. However, in order to diagnose pathological sleepiness during the day, patients are required to obtain over 10 points in the ESS [65]. We discovered that participants who got over 10 points in the ESS had a lower minimal duration of moaning episodes. Patients also frequently reported family concerns over their health, the sensation of a dry mouth in the mornings, or nocturnal noises. Snoring and symptoms such as abnormal patterns of sleep breathing were found to prolong the minimal time of the catathrenia episodes. One of the most reported complaints of catathrenia embraced sensation of a dry mouth and EDS which may be also an OSA symptom [66,67,68,69]. However, according to our analysis, OSA is not the most frequent among sleep disorders co-existing with catathrenia. Therefore, it is an interesting issue whether there exists a common pathway for OSA and catathrenia manifested by similar symptoms. Unfortunately, literature did not describe potential common mechanisms for OSA and catathrenia. But Songu et al. showed CPAP treatment improved catathrenia [33]; thus, a common pathway may exist. Moreover, similar symptoms of catathrenia without reporting nocturnal groaning may imitate the OSA disorder and without PSG conducting, catathrenia may be misdiagnosed. Nocturnal behaviors were reported by patients’ families, because patients are often unaware of the moaning [24]. Therefore, the reported complaints have to be taken into consideration very carefully, especially in conditions such as catathrenia, which we do not, as yet, fully understand. Families could also embellish the reported symptoms. One such family had reported hearing groaning from their son, that was so loud, they were afraid to go camping due to concerns that they may be attacked by bears, who might think that the sound is coming from a hurt, dying animal [50]. Other descriptions of groaning included purring or sexual connotations [28, 40]. According to an objective analysis of episode vocalization, the most common vocalization was the type I sound with a sinusoidal waveform, followed by the type II sound with a semi-rhythmic sawtooth waveform, which consistently indicated the vocal origin of the episodes [19]. The lack of atypical sounds was confirmed during PSG study.
Almost half the analyzed population reported their awareness about occurring catathrenia episodes at home. In fact, according to patients’ history, 30% of the participants experienced episodes almost every single night at home. These episodes were determined to have a moderate relationship with the REM sleep, which is partially confirmed that occurring catathrenia episodes according to ICSD-3. This is in contrast to our overall results, where episodes of catathrenia appeared more frequently during the NREM cycle. To diagnose catathrenia, PSG was used in the majority of the studied patients. Numerous treatment modalities were described including CPAP therapy, pharmacotherapy, the utilization of a mandibular advancement device (MAD), and botulinum toxin. CPAP therapy was the most commonly used form of treatment and is the standard therapy for sleep-breathing disorders (SDB), allowing to improve patient quality of life, reducing EDS and causing a reduction in blood pressure values [70]. Patients with catathrenia who underwent CPAP therapy were found to have episodes that occurred most frequently during the NREM sleep phase. Our analysis found that CPAP therapy also caused a reduction in the maximal duration of the groaning episodes, which may indicate the respiratory origin of catathrenia.
Despite conducting a reliable analysis of the available data regarding catathrenia, our study does have a number of limitations. First of all, catathrenia is a rare condition and our analysis was based on few papers, which did not always contain the entire patient’s history and did not thoroughly analyze the features of catathrenia. Almost every study focused on different features of catathrenia. Therefore, each parameter that was analyzed had a different number of participants. The largest amount of data came from single studies. However, even if the studies presented a cohort of patients, these publications were deemed to have a high or moderate risk of bias. There were also a number of papers that embraced the subject of catathrenia; however, we could not classify these studies even as case reports. As a result, we could not extract their data and use it in our analysis. Unfortunately, due to a lack of access to some new studies focusing on catathrenia, our article does not contain some important pieces of knowledge. Taking into consideration all of these limitations, future studies will have to include the detailed features of catathrenia in cohort patients and explain the potential long-term consequences of catathrenia on patients’ health. These studies will also have to take into consideration the relationship between patients’ status and catathrenia features.
Conclusions
Catathrenia occurs with similar frequency in both genders. The most frequent complaints of the patients with catathrenia are groaning or other atypical nocturnal sounds, awareness of disturbing bedpartners, snoring, and daytime somnolence—although not confirmed by ESS. The episodes of catathrenia occur more frequently in NREM than in REM sleep. However, at home episodes occurred according to ICSD-3 in REM sleep. Obesity and aging reduce the duration of these episodes. Catathrenia may be considered as a sex-specific condition, because as compared with males in females its episodes occur more frequently in NREM than in REM sleep and are characterized by longer minimal duration. There is no influence of the comorbidities on the incidence of catathrenia. However, some systemic diseases may be associated with shorter minimal and maximal duration of its episodes, as well as with lower ESS score. The effects of CPAP treatment leading to shortening of the maximal duration of the episodes of catathrenia may indicate the respiratory origin of catathrenia.
Data availability
Data available on request.
Change history
27 June 2024
A Correction to this paper has been published: https://doi.org/10.1007/s11325-024-03088-z
Abbreviations
- ICSD-2:
-
International Classification of Sleep Disorders, version 2
- ICSD-3:
-
International Classification of Sleep Disorders, version 3
- REM:
-
Rapid eye movement
- NREM:
-
Non-rapid eye movement
- PSG:
-
Polysomnography
- OSA:
-
Obstructive sleep apnea
- PRISMA 2020:
-
Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020
- ESS:
-
Epworth Sleepiness Scale
- JBI:
-
The Joanna Briggs Institute
- SD:
-
Standard deviation
- EDS:
-
Excessive daytime sleepiness
- BMI:
-
Body mass index
- CPAP:
-
Continuous Positive Airway Pressure
- SB:
-
Sleep bruxism
- ADHD:
-
Attention-deficit hyperactivity disorder
- Fig:
-
Figure
- MAD:
-
Mandibular advancement device
References
Huyett P, Siegel N, Bhattacharyya N (2021) Prevalence of sleep disorders and association with mortality: results from the NHANES 2009–2010. Laryngoscope 131:686–689. https://doi.org/10.1002/lary.28900
McArdle N, Ward SV, Bucks RS, Maddison K, Smith A, Huang R-C et al (2020) The prevalence of common sleep disorders in young adults: a descriptive population-based study. Sleep 43:zsaa072. https://doi.org/10.1093/sleep/zsaa072
Shi L, Chen S-J, Ma M-Y, Bao Y-P, Han Y, Wang Y-M et al (2018) Sleep disturbances increase the risk of dementia: a systematic review and meta-analysis. Sleep Med Rev 40:4–16. https://doi.org/10.1016/j.smrv.2017.06.010
Murphy MJ, Peterson MJ (2015) Sleep disturbances in depression. Sleep Med Clin 10:17–23. https://doi.org/10.1016/j.jsmc.2014.11.009
McDermott M, Brown DL, Chervin RD (2018) Sleep disorders and the risk of stroke. Expert Rev Neurother 18:523–531. https://doi.org/10.1080/14737175.2018.1489239
Ferini-Strambi L, Galbiati A, Combi R (2019) Sleep disorder-related headaches. Neurol Sci 40:107–113. https://doi.org/10.1007/s10072-019-03837-z
Li C, Shang S (2021) Relationship between sleep and hypertension: findings from the NHANES (2007–2014). Int J Environ Res Public Health 18:7867. https://doi.org/10.3390/ijerph18157867
von Schantz M, Ong JC, Knutson KL (2021) Associations between sleep disturbances, diabetes and mortality in the UK Biobank cohort: a prospective population-based study. J Sleep Res 30:e13392. https://doi.org/10.1111/jsr.13392
Ge X, Han F, Huang Y, Zhang Y, Yang T, Bai C et al (2013) Is obstructive sleep apnea associated with cardiovascular and all-cause mortality? PLoS ONE 8:e69432. https://doi.org/10.1371/journal.pone.0069432
Sia C-H, Hong Y, Tan LWL, van Dam RM, Lee C-H, Tan A (2017) Awareness and knowledge of obstructive sleep apnea among the general population. Sleep Med 36:10–17. https://doi.org/10.1016/j.sleep.2017.03.030
Pérez-Carbonell L, Mignot E, Leschziner G, Dauvilliers Y (2022) Understanding and approaching excessive daytime sleepiness. Lancet 400:1033–1046. https://doi.org/10.1016/S0140-6736(22)01018-2
Michalek-Zrabkowska M, Wieckiewicz M, Macek P, Gac P, Smardz J, Wojakowska A et al (2020) The relationship between simple snoring and sleep bruxism: a polysomnographic study. Int J Environ Res Public Health 17:8960. https://doi.org/10.3390/ijerph17238960
Guilleminault C, Poyares D, da Rosa A, Kirisoglu C, Almeida T, Lopes MC (2006) Chronic fatigue, unrefreshing sleep and nocturnal polysomnography. Sleep Med 7:513–520. https://doi.org/10.1016/j.sleep.2006.03.016
Brownlow JA, Miller KE, Gehrman PR (2020) Insomnia and cognitive performance. Sleep Med Clin 15:71–76. https://doi.org/10.1016/j.jsmc.2019.10.002
Porwal A, Yadav YC, Pathak K, Yadav R (2021) An update on assessment, therapeutic management, and patents on insomnia. Biomed Res Int 2021:6068952. https://doi.org/10.1155/2021/6068952
Alonso J, Camacho M, Chhetri DK, Guilleminault C, Zaghi S (2017) Catathrenia (nocturnal groaning): a social media survey and state-of-the-art review. J Clin Sleep Med 13:613–622. https://doi.org/10.5664/jcsm.6556
Siddiqui F, Walters AS, Chokroverty S (2008) Catathrenia: a rare parasomnia which may mimic central sleep apnea on polysomnogram. Sleep Med 9:460–461. https://doi.org/10.1016/j.sleep.2007.10.012
Argollo NS, Parreira DR, Pereira LC (2021) The importance of audio-video documentation during polysomnography for diagnosis of catathrenia in a 6-year-old child: case report. Sleep Sci 14:390–393. https://doi.org/10.5935/1984-0063.20200122
Yu M, Wen Y, Xu L, Han F, Gao X (2020) Polysomnographic characteristics and acoustic analysis of catathrenia (nocturnal groaning). Physiol Meas 41:125012. https://doi.org/10.1088/1361-6579/abd235
Guilleminault C, Hagen CC, Khaja AM (2008) Catathrenia is not expiratory snoring. Sleep 31:774–775. https://doi.org/10.1093/sleep/31.6.774
Drakatos P, Higgins S, Duncan I, Stevens S, Dastagir S, Birdseye A et al (2017) Catathrenia as a REM predominant disorder of arousal. Sleep Med 32:222–226. https://doi.org/10.1016/j.sleep.2016.06.010
Vetrugno R, Provini F, Plazzi G, Vignatelli L, Lugaresi E, Montagna P (2001) Catathrenia (nocturnal groaning): a new type of parasomnia. Neurology 56:681–683. https://doi.org/10.1212/wnl.56.5.681
Katz ES, D’Ambrosio C (2023) Catathrenia in children: clinical presentation, polysomnographic features, natural history, and response to therapy. J Clin Sleep Med 19(8):1505–1511. https://doi.org/10.5664/jcsm.10582
Iriarte J, Campo A, Alegre M, Fernández S, Urrestarazu E (2015) Catathrenia: respiratory disorder or parasomnia? Sleep Med 16:827–830. https://doi.org/10.1016/j.sleep.2014.12.026
Yu M, Hao Z, Xu L, Wen Y, Han F, Gao X (2021) Mandibular advancement device as treatment trial for catathrenia (nocturnal groaning). J Clin Sleep Med 17:1767–1776. https://doi.org/10.5664/jcsm.9290
Poli F, Ricotta L, Vandi S, Franceschini C, Pizza F, Palaia V et al (2012) Catathrenia under sodium oxybate in narcolepsy with cataplexy. Sleep Breath 16:427–434. https://doi.org/10.1007/s11325-011-0520-2
Villafuerte-Trisolini B, Adrianzén-Álvarez F, Duque KR, Palacios-García J, Vizcarra-Escobar D (2017) Cyclic alternating pattern associated with catathrenia and bruxism in a 10-year-old patient. J Clin Sleep Med 13:511–512. https://doi.org/10.5664/jcsm.6510
Bar C, Pedespan J-M, Ghorayeb I (2016) Catathrenia in a four-year-old boy: a first case report. Sleep Med 20:131–133. https://doi.org/10.1016/j.sleep.2015.12.014
Ott SR, Hamacher J, Seifert E (2011) Bringing light to the sirens of night: laryngoscopy in catathrenia during sleep. Eur Respir J 37:1288–1289. https://doi.org/10.1183/09031936.00083510
Ramar K, Olson EJ, Morgenthaler TI (2008) Catathrenia. Sleep Med 9:457–459. https://doi.org/10.1016/j.sleep.2007.08.011
Abbasi AA, Morgenthaler TI, Slocumb NL, Tippmann-Peikert M, Olson EJ, Ramar K (2012) Nocturnal moaning and groaning-catathrenia or nocturnal vocalizations. Sleep Breath 16:367–373. https://doi.org/10.1007/s11325-011-0503-3
Romigi A, Vitrani G, D’Aniello A, Di Gennaro G (2014) Can nocturnal groaning be suspected by cardiorespiratory polygraphy? Sleep Med 15:1002–1004. https://doi.org/10.1016/j.sleep.2014.03.013
Songu M, Yilmaz H, Yuceturk AV, Gunhan K, Ince A, Bayturan O (2008) Effect of CPAP therapy on catathrenia and OSA: a case report and review of the literature. Sleep Breath 12:401–405. https://doi.org/10.1007/s11325-008-0194-6
Pevernagie DA, Boon PA, Mariman AN, Verhaeghen DB, Pauwels RA (2001) Vocalization during episodes of prolonged expiration: a parasomnia related to REM sleep. Sleep Med 2:19–30. https://doi.org/10.1016/s1389-9457(00)00039-3
JBI Critical Appraisal Tools | JBI (n.d.). https://jbi.global/critical-appraisal-tools. Accessed 26 Jul 2023
Sterne JA, Hernán MA, Reeves BC, Savović J, Berkman ND, Viswanathan M et al (2016) ROBINS-I: a tool for assessing risk of bias in non-randomised studies of interventions. BMJ 355:i4919. https://doi.org/10.1136/bmj.i4919
Prihodova I, Sonka K, Kemlink D, Volna J, Nevsimalova S (2009) Arousals in nocturnal groaning. Sleep Med 10:1051–1055. https://doi.org/10.1016/j.sleep.2008.09.019
Oldani A, Manconi M, Zucconi M, Castronovo V, Ferini-Strambi L (2005) ‘Nocturnal groaning’: just a sound or parasomnia? J Sleep Res 14:305–310. https://doi.org/10.1111/j.1365-2869.2005.00460.x
Vetrugno R, Lugaresi E, Plazzi G, Provini F, D’Angelo R, Montagna P (2007) Catathrenia (nocturnal groaning): an abnormal respiratory pattern during sleep. Eur J Neurol 14:1236–1243. https://doi.org/10.1111/j.1468-1331.2007.01954.x
Guilleminault C, Hagen CC, Khaja AM (2008) Catathrenia: parasomnia or uncommon feature of sleep disordered breathing? Sleep 31:132–139. https://doi.org/10.1093/sleep/31.1.132
Koo DL, Hong SB, Joo EY (2012) Acoustic characteristic of catathrenia and snoring: different subtypes of catathrenia. Sleep Med 13:961–964. https://doi.org/10.1016/j.sleep.2012.04.002
Overland B, Akre H, Berdal H, Skatvedt O (2012) Sleep-related groaning: prevalence and characteristics in a cohort of patients with suspected obstructive sleep apnea. Acta Otolaryngol 132:90–95. https://doi.org/10.3109/00016489.2011.624119
Drakatos P, Higgins S, Duncan I, Stevens S, Dastagir S, Birdseye A et al (2017) Catathrenia, a REM predominant disorder of arousal? Sleep Med 32:222–226. https://doi.org/10.1016/j.sleep.2016.06.010
Pérez-Carbonell L, Muñoz-Lopetegi A, Sánchez-Valle R, Gelpi E, Farré R, Gaig C et al (2022) Sleep architecture and sleep-disordered breathing in fatal insomnia. Sleep Med 100:311–346. https://doi.org/10.1016/j.sleep.2022.08.027
Kazaglis L (2018) The value of a well-trained ear: incidental detection of catathrenia on home sleep apnea tests in patients with low probability for obstructive sleep apnea. J Clin Sleep Med 14:2083–2086. https://doi.org/10.5664/jcsm.7544
Steinig J, Lanz M, Krügel R, Happe S (2008) Breath holding - a rapid eye movement (REM) sleep parasomnia (catathrenia or expiratory groaning). Sleep Med 9:455–456. https://doi.org/10.1016/j.sleep.2007.08.008
Tereshko Y, Lettieri C, Gigli GL, Nilo A, Garbo R, Valente M (2022) Turning off the siren of the night: botulinum toxin for the treatment of nocturnal groaning. A case series Sleep Med 92:15–18. https://doi.org/10.1016/j.sleep.2022.03.002
Iriarte J, Fernández S, Fernandez-Arrechea N, Urrestarazu E, Pagola I, Alegre M et al (2011) Sound analysis of catathrenia: a vocal expiratory sound. Sleep Breath 15:229–235. https://doi.org/10.1007/s11325-010-0420-x
Manconi M, Zucconi M, Carrot B, Ferri R, Oldani A, Ferini-Strambi L (2008) Association between bruxism and nocturnal groaning. Mov Disord 23:737–739. https://doi.org/10.1002/mds.21885
Grigg-Damberger M, Brown LK, Casey KR (2006) A cry in the night: nocturnal moaning in a 12-year-old boy. Sleep-related groaning (Catahrenia). J Clin Sleep Med 2:354–7
Bansal R, Kodali L, Weingarten JA (2015) Nocturnal groaning: strange sounds in the night. Ann Am Thorac Soc 12:128–130. https://doi.org/10.1513/AnnalsATS.201407-316CC
Motojima T, Fujii K, Ohashi H, Arakawa H (2018) Catathrenia in Pitt-Hopkins syndrome associated with 18q interstitial deletion. Pediatr Int 60:479–481. https://doi.org/10.1111/ped.13514
Gómez T, Casal A, De Miguel MDPC, Rodríguez PR, Acevedo MFT, De Blas FE (2020) Catathrenia resolved with the lowest CPAP pressure settings. Pulmonology 26:107–110. https://doi.org/10.1016/j.pulmoe.2019.07.010
Carbajal-Mamani S, Berry RB, Al Hourani L, Khatri A, Ryals S, Wagner MH (2021) Knuckle cracking at night associated with sodium oxybate treatment. J Clin Sleep Med 17:1121–1123. https://doi.org/10.5664/jcsm.9112
Dhingra R, Vasan RS (2012) Age as a risk factor. Med Clin North Am 96:87–91. https://doi.org/10.1016/j.mcna.2011.11.003
Jura M, Kozak LP (2016) Obesity and related consequences to ageing. Age (Dordr) 38:23. https://doi.org/10.1007/s11357-016-9884-3
American Academy of Sleep Medicine (ed) (2014) International classification of sleep disorders, 3rd edn. American Academy of Sleep Medicine e11, p 303
Pengo MF, Won CH, Bourjeily G (2018) Sleep in women across the life span. Chest 154:196–206. https://doi.org/10.1016/j.chest.2018.04.005
Cappadona R, De Giorgi A, Di Simone E, Zucchi B, Rodriguez-Borrego MA, Lopez-Soto PJ et al (2021) Sleep, dreams, nightmares, and sex-related differences: a narrative review. Eur Rev Med Pharmacol Sci 25:3054–65. https://doi.org/10.26355/eurrev_202104_25559
Hao Z, Xu L, Zhang J, Lan X, Gao X, Han F (2016) Anatomical characteristics of catathrenia (nocturnal groaning) in upper airway and orofacial structures. Sleep Breath 20:103–111. https://doi.org/10.1007/s11325-015-1191-1
Buyse B, Kalkanis A, Testelmans D (2023) Catathrenia in severe obstructive sleep apnea: a novel entity never described before. Sleep Med 112:239–245. https://doi.org/10.1016/j.sleep.2023.10.023
Nozawa S, Urushihata K, Machida R, Hanaoka M (2022) Sleep architecture of short sleep time in patients with obstructive sleep apnea: a retrospective single-facility study. Sleep Breath 26:1633–1640. https://doi.org/10.1007/s11325-021-02533-7
Avila C, Holloway AC, Hahn MK, Morrison KM, Restivo M, Anglin R et al (2015) An overview of links between obesity and mental health. Curr Obes Rep 4:303–310. https://doi.org/10.1007/s13679-015-0164-9
Gonçalves MT, Malafaia S, Moutinho Dos Santos J, Roth T, Marques DR (2023) Epworth sleepiness scale: a meta-analytic study on the internal consistency. Sleep Med 109:261–9. https://doi.org/10.1016/j.sleep.2023.07.008
Rosenberg R, Babson K, Menno D, Morris S, Baladi M, Hyman D et al (2022) Test–retest reliability of the Epworth Sleepiness Scale in clinical trial settings. J Sleep Res 31:e13476. https://doi.org/10.1111/jsr.13476
Oksenberg A, Froom P, Melamed S (2006) Dry mouth upon awakening in obstructive sleep apnea. J Sleep Res 15:317–320. https://doi.org/10.1111/j.1365-2869.2006.00527.x
Ma X, Zhang C, Wang Y, Yu K, Jin Z, Zhang C et al (2024) Correlation of morning dry mouth with clinical features of OSA in a community population: a cross-sectional study. Postgrad Med 136:30–35. https://doi.org/10.1080/00325481.2024.2303972
Zhang C, Shen Y, Liping F, Ma J, Wang G-F (2021) The role of dry mouth in screening sleep apnea. Postgrad Med J 97:294–298. https://doi.org/10.1136/postgradmedj-2020-137619
Błaszczyk B, Martynowicz H, Więckiewicz M, Straburzyński M, Antolak M, Budrewicz S et al (2024) Prevalence of headaches and their relationship with obstructive sleep apnea (OSA) - systematic review and meta-analysis. Sleep Med Rev 73:101889. https://doi.org/10.1016/j.smrv.2023.101889
Cao MT, Sternbach JM, Guilleminault C (2017) Continuous positive airway pressure therapy in obstuctive sleep apnea: benefits and alternatives. Expert Rev Respir Med 11:259–272. https://doi.org/10.1080/17476348.2017.1305893
Author information
Authors and Affiliations
Contributions
HM and BB were involved in the conception, visualization, and supervision of the study. BB, GL, DN, and MMZ collected the data and wrote the manuscript. AW, AB, MW, and GM were involved in the revision of final version of the manuscript. All authors have agreed to the published version of the manuscript. All authors have seen and agreed to the published version of the manuscript.
Corresponding author
Ethics declarations
Ethical approval
This article does not contain any studies with human participants performed by any of the authors.
Conflict of interest
The authors declare no competing interests.
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
In the originally published version of this article, the name of the third author was incorrectly spelled as "Mieszko Wieckiewcz". The correct name is “Mieszko Wieckiewicz”. Also, the correct affiliation for Monika Michalek‑Zrabkowska, Gabriella Lachowicz, Grzegorz Mazur, and Helena Martynowicz is “Department of Internal Medicine, Occupational Diseases, Hypertension and Clinical Oncology, Wroclaw Medical University, 50-556 Wroclaw, Poland.”
Supplementary Information
Below is the link to the electronic supplementary material.
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
About this article
Cite this article
Blaszczyk, B., Wichniak, A., Wieckiewicz, M. et al. The clinical characteristic of catathrenia: a new look at an old issue—a systematic review of existing literature. Sleep Breath 28, 1523–1537 (2024). https://doi.org/10.1007/s11325-024-03033-0
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11325-024-03033-0