Introduction

Stroke is a leading cause of disability worldwide with grave morbidity and mortality [1]. It is the second cause of death in Egypt, after ischemic heart disease with a high prevalence of 963/100000 populations [2]. Along with expeditious acute management, efficient secondary prevention and consistent rehabilitation, sleep disorders’ management has a hand in offering a medical service up to the mark.

Ain Shams University Hospital is a tertiary center for neurology and an accredited center for offering comprehensive stroke services in the region through our stroke unit and stroke outpatient clinic.

Sleep disorders are growingly recognized as a salient consideration while management of different neurological diseases and stroke specifically [3,4,5,6], though its weightiness, only about 6% of stroke survivors are offered formal sleep testing and an estimated 2% complete such testing in the 3-month post-stroke period. That may be ought to uncertain timing for proper sleep testing after a stroke [7], added to inadequate awareness about sleep disorders and implication on stroke’s outcome and overwhelming with vascular treatment.

From practical point of view, sleep disorders sometimes may be in the dark side of the tunnel, some physicians are reluctant about navigating this area in the history, especially if it did not come to patient’s attention as restless leg syndrome, periodic leg movement, parasomnia, as those antecedent disorders in the context of surviving stroke patient are usually forgotten, to the contrary of insomnia, or excessive day time sleepiness; however, the later may be misinterpreted as fatigue or sleepiness from a stroke.

So, this study was done to improve awareness about post-stroke sleep disorders among physicians and healthcare practitioners dealing with stroke patients.

Aim of the work

Description of prevalence of sleep disorders in patients who survived stroke and the severity and magnitude of these disorders and to study the correlation between sleep disorders post-stroke and stroke demographic, clinical and risk factor variables, and to spotlight an easy approach for post-stroke sleep screening.

Subjects and methods

This is a cross-sectional prospective study, 75 patients were selected from the attendees of stroke outpatient clinic at Ain Shams University Hospital from January 2015 to December 2015. Their routine investigational data were recorded (magnetic resonance image on the brain (MRI), magnetic resonance angiography for brain (MRA), electrocardiography (ECG), echocardiography, vertebrobasilar and carotid duplex, hemoglobin A1c (HbA1c) level, lipid profile: cholesterol (CH), triglycerides (TGs) and low-density lipoprotein (LDL).

Patients were subjected to full neurological history and examination, structured sheet of sleep questionnaire, and were interviewed by the following questionnaires: structured sheet for sleep questionnaire [7], Pittsburg Sleep Quality Index (PSQI) [8], Epworth sleepiness scale (ESS) [9], Apnea/Hypopnea Index (AHI) Arabic version Additional file 1 [7].

Inclusion criteria of the patients were as followed:

  1. 1-

    First-ever stroke either ischemic or hemorrhagic.

  2. 2-

    The interval between the onset of stroke symptoms and the date of the interview does not exceed 12 weeks (3 months).

  3. 3-

    Age range between 18 years and 70 years old.

Exclusion criteria were:

  1. 1-

    Subarachnoid hemorrhage and cerebral sinus thrombosis.

  2. 2-

    Primary sleep disorders prior to stroke onset.

  3. 3-

    Patients who had end-stage medical illness and those with a neurological disease or a psychiatric disorder known to affect sleep. In addition, patients who were on medications reputed to affect sleep physiology.

Statistical analysis

Data were analyzed using SPSS version 20. Qualitative data were presented as numbers and percentages. Chi-square test and/or Fisher exact test were used for qualitative data which was used instead of chi-square test when the expected count in any cell was found less than 5. The confidence interval was set to 95% and the margin of error accepted was set to 5 %. P value was considered significant as the following: P > 0.05: non-significant, P < 0.05: significant, P < 0.01: highly significant.

Results

Our sample included 75 patients with 34 (45.3 %) males and 41 ( 54.7%) females, mean age ± standard deviation (SD) 59.3 ± 5.34, 70.6 % were shown to have sleep disorders, the details are shown in Table 1; in addition, Fig. 1 showed different sleep phenomena accounted for in our patients.

Table 1 Sleep disorders and phenomenon after stroke
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Fig. 1
figure 1

Distribution of sleep phenomenon and complaints in our patients’ sample, with SDB being the highest and EDS came second in the rank, while middle sleep insomnia accounted for the least percentage

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Fig. 2
figure 2

Different sleep disorders and relation with the site of the lesion

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The detailed data by applying the nominated sleep questionnaires revealed that 17.3 % suffered from severe EDT, i.e., score more than 16, coming to sleep-disordered breathing 14 (18.7%) patients had a moderate form of apnea while 8 (10.6 %) patients suffered from a severe degree of apnea. And on the whole, 61.3 % were poor sleepers, i.e., score more than 5 in the Pittsburg sleep scale [8] (Table 2).

Table 2 Data of the applied questionnaires
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Upon correlation between different sleep disorders and stroke risk factors, it was found that non-cardiac patients have more prevalence of different sleep disorders; however, this was not statistically different from cardiac patients (Table 3).

Table 3 Statistical correlations between sleep disorders after stroke and stroke risk factors
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Sleep complaints were more common in moderate stroke according to the NIHSS scale (very severe > 25, severe 15–24, mild to moderately severe 5–14, mild 1–5 ) [10], however, with no statistical significance. Moreover, it is higher during the first 4 weeks after stroke but with no statistical difference as well. In the first few weeks after stroke, the patient is exposed to this new stressor that has provoked the occurrence of the nominated disorders (Table 4).

Table 4 Statistical correlations between sleep disorders after stroke and stroke clinical variables
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Figure 2 Demonstrates the relationship between stroke site and different sleep disorders.

Discussion

Sleep is a complex process that involves many areas in the brain including the pedunculopontine nucleus (PPD), lateral dorsal tegmentum (LDT), locus coeruleus (LC), preoptic area, posterior hypothalamus, and a flip flop switch in a harmonious manner. Moreover, many neurotransmitters are involved in this process [11]. So, any condition that leads to disruption of the aforementioned components would affect sleep, this includes many neurological disorders, and far and away stroke comes in the center.

Though sleep disorders are widely prevalent and markedly transform the quality of life status of patients, they are usually a forsaken category by physicians while managing a stroke patient, whether acutely or during secondary prevention plan. There are no clear guidelines on how to deal with these disorders after a stroke or throughout the secondary prevention journey. In addition, that topic is not under spotlights in the regional and national stroke conferences and meetings.

This study used an easy applicable questionnaire, which is quick to perform, and thus constitute a tool that could be practically applied in everyday practice.

As mooted earlier, sleep and stroke have definite relationship, stroke affects sleep microstructures in different ways, different studies indicated an association between different stroke sites and or side of stroke and the affection of REM and non-REM sleep [12, 13]. Moreover, different markers as il-1, IL-6, and TNF-α that are incremented in a stroke had been found to result from sleep deprivation and insomnia [14,15,16,17,18]; hence, early detection of sleep disorders is mandatory to prevent further damage.

A respectable sector of stroke patients (20%–63%) manifests by different sleep disorders as hypersomnia, insomnia, parasomnias, circadian rhythm disorders, periodic limb movement disorder, and sleep-disordered breathing [19]. In our study, it was found that 70.6 % had sleep disorders, auscultating raised points in this discussion, it is definitely an enormous issue.

Hence, sympathetic overactivity and reduced cerebral blood flow are the suggested mechanisms for the occurrence of some sleep disorders like insomnia, SDB [20], and periodic leg movements, as well as instigation of the development of stoke. Proper management of these disorders is mandatory for stroke secondary prevention and might unfold and clear up reasons behind recurrent strokes in optimally treated patients. In a recent study, earlier this year (the basic project) that used a survey on 842 patients with stroke in south Texas, SDB represented a modifiable factor associated with a higher rate of recurrent stroke and poor functional outcome [21].

SDB is more prevalent in stroke than non-stroke patients [22], in our study, 29.3 % had possible SDB by the Apnea index questionnaire to be confirmed by polysomnography, different studies reported a prevalence rate range between 43 and 72%, higher prevalence might be attributed to preexisting SDB and not counting de novo cases only [23,24,25]. In a study done in Switzerland, better stroke outcome, and less morbidity and mortality was associated with a lower Apnea, and Apnea/Hypopnea Index [22]. Under recognition of SDB lead to high functional impairment in the long term.

Furthermore, in a systematic review about insomnia after stroke, it was found that insomnia prevalence ranges from 14 % to 59 % in studies used clinical diagnostic tools and 19.8% to 69% using non-clinical diagnostic tools and a variety of diagnostic questionnaires, and in that systematic review, one study reported association between cortical lesions and poor sleep quality [26], in our cross-sectional study insomnia prevalence was 14.7 % with 10.7 % had initial insomnia. Insomnia stands as independent risk factor for cerebrovascular reactivity (CVR) and aggravation of sympathetic hyperactivity [27], thus early detection and management is mandatory. Different factors enact in this as the external environment in the stroke unit (frequent medication, stress related to the recently developed illness, frequent medication), comorbid psychiatric disorders such as anxiety and depression, in addition to the effect of the inflammatory mediators released by the damaged tissue as mentioned earlier in this text.

This study has a limitation that polysomnography was not done to confirm the presence of different as sleep-disordered breathing and parasomnia. But it represents a simple bedside screening way for the detection of post-stroke sleep disorders that would help physicians and healthcare personals who are engaged with stroke patients to better manage these disorders.

In conclusion, sleep and stroke have a definite relationship, sleep disorders are broadly prevailing after stroke, and resulting damage hinders the process of rehabilitation, and holds up neuronal plasticity and consequently impecunious functional outcome. Simple questionnaires are easy applicable methods for screening of such disorders post-stroke. Guidelines needed regarding screening and management of Sleep disorders after the stroke through further larger cohort studies.