Introduction

Menopause is the complete cessation of menstruation and indicates the end of reproduction [1]. Menopause is a normal state in which symptoms are often well managed, but it can be debilitating for some women and therefore can be detrimental to their health [2,3,4]. A decrease in estrogen production and resulting increase in follicle-stimulating hormone cause follicular atrophy which is the main cause of menopause [4]. Sleep is a complex process with the brain in an active state of anesthesia [5]. Sleep disorders are determined by tools such as self-report questionnaires, polysomnography, and actigraphy [6, 7]. Irregular sleep and daytime sleepiness are common among the general public and are among the most important examples of sleep disorders and resulting symptoms [5,6,7].

Reports of sleep disorders vary greatly and prevalence has been reported to be between 12 and 79% among women [7, 8]. Sleep disorders have many negative effects on health. These include increased risk of chronic diseases, decreased daily functioning, decreased mood, reduced use of healthcare, and female sexual dysfunction [9,10,11].

About a third of women’s lives around the world are affected by sleep and menopause, and both of these have a large effect on health [12]. Disturbance in falling asleep, disturbance in staying awake during the day and during work activities, and disturbance in the circadian rhythm are indicators that can help in diagnosis [13].

Studies that have examined the symptoms of postmenopausal women report that most of these women have obstructive sleep apnea [13]. In premenopause ages, the prevalence of such sleep disorders approximates 42%, in perimenopause ages 47%, and in postmenopause ages 60% [13,14,15,16]. Given the increasing number of postmenopausal women, as well as the importance of sleep quality in these individuals, the aim of this study was to perform a meta-analysis on sleep disorders during menopause in order to guide health professionals and experts in this field.

Methods

The initial search was conducted in February 2022 and last updated in April 2022. To find relevant articles, the Embase, ScienceDirect, Scopus, WoS, PubMed, and Google Scholar databases were checked.

The keywords examined in order to search in the reported databases included: Sleep Disturbance, Sleep Problems, Sleep Deprivation, Sleep Disorders, Sleep, Menopause, Long Sleeper Syndrome, Restless Leg Syndrome, Short Sleeper Syndrome, Sleep Wake Disorders, Obstructive Sleep Apnea.

Studies included in the review

Observational studies that reported prevalence of sleep disorders, articles written in English, and also, articles with English abstracts translated for non-English speakers.

Studies not included in the review

Studies whose full text was unavailable, case reports, interventional studies.

The method of selecting and extracting studies in the systematic review

Studies were reviewed based on the inclusion and exclusion criteria and irrelevant items were removed. Data were entered into EndNote software in order to remove duplicate articles. All review steps were performed by three reviewers independently in order to avoid mistakes in reviewing studies and extracting data. All stages of reviewing articles followed PRISMA guidelines [14].

Determining the quality of articles and statistical analysis of meta-analysis

The STROBE checklist was used to check the quality of observational studies [15]. Based on the scores reported in STROBE, those studies with scores above 16 were considered high-quality articles. The extracted information was entered into the Comprehensive Meta-Analysis software and publication bias was checked with funnel plot and heterogeneity was checked with the I2 test.

Results

A total of 3998 articles were identified within the searched databases and 63 articles were identified through a manual search. After exclusions, 41 studies remained for the meta-analysis. The studies were identified after following the four steps of the PRISMA guidelines (Fig. 1). The information in these articles is listed in Table 1.

Fig. 1
figure 1

The process of reviewing, screening, and determining the final articles based on the PRISMA process

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Table 1 Information extracted from final studies
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The prevalence of sleep disorders among postmenopausal women was 51.6% (95% CI: 44.6–58.5%) (Fig. 2). Heterogeneity of studies (I2: 98.4) and publication bias in studies were not significant (p: 0.596) (Fig. 3).

Fig. 2
figure 2

The overall prevalence of sleep disorders among postmenopausal women

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Fig. 3
figure 3

Funnel plot to investigate the publication bias in studies

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The meta-regression test showed that the larger the sample in the studies, the lower the overall prevalence of sleep disorders in postmenopausal women. (Fig. 4). Also, with the upward and increasing trend of studies until 2020 (Fig. 5), the sleep disorders among postmenopausal women have decreased (p < 0.05).

Fig. 4
figure 4

Evaluate the effect of sample size on the overall prevalence of sleep disorders among postmenopausal women

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Fig. 5
figure 5

Evaluate the effect of year studies on the overall prevalence of sleep disorders among postmenopausal women

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Based on the subgroup analysis results reported in Table 2, the highest sleep disorder among postmenopausal women was 54.7% (95% CI: 47.2–62.1%) (Table 2).

Table 2 Overall prevalence of sleep disorders among postmenopausal women by menopausal stages
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Based on the subgroup analysis results reported in Table 3, the highest sleep disorders among postmenopausal women were related to restless legs syndrome (RLS) with 63.8% (95% CI: 10.6–96.3%) (Table 3).

Table 3 Prevalence of various sleep disorders among postmenopausal women
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Based on Table 4, it was found that for sleep apnea, the highest prevalence was related to postmenopause with a prevalence of 35.2% (95% CI: 12.9–66.5%); for RLS, the highest prevalence was related to postmenopause with a prevalence of 53.1% (95% CI: 3.1–97.6%); for insomnia , the highest prevalence is related to perimenopause with a prevalence of 37.6% (95% CI: 28.5–47.7%); for sleepiness, the highest prevalence was in postmenopause with a prevalence of 34.2% (95% CI: 8.5–74.5%); and for wake disorders, the highest prevalence was in postmenopause with 14.2% (95% CI: 7.1–26.4%) (Table 4).

Table 4 Prevalence of various sleep disorders in postmenopausal women by menopausal stage
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Discussion

Based on the results of the analysis, the overall prevalence of sleep disorders in all studies was 51.6%. Shafie et al. reported the sleep disorders during postmenopause were 52.2%, in perimenopause 38.4%, and in premenopause 33.7%. These results show that the prevalence of sleep disorders during postmenopause is higher than that in the premenopause and perimenopause stages [19]. Additionally, in a study by Waidyasekera et al., sleep disorders were reported to be 39.6% in the postmenopause stage, 31.1% in perimenopause, and 25.7% among women in the premenopause period [52]. A study by Castro et al. in 2021 in Colombia and during the coronavirus outbreak reported that the sleep disorder was 65.1% in the postmenopause and 54.5% in the premenopause stage [53].

Studies have shown that 47 to 67% of postmenopausal women have OSA [54, 55]. The combination of factors such as weight gain and increase in BMI index as well as an increase in waist-to-hip ratio after menopause leads to changes in the upper airway and causes obstructive sleep apnea and sleep disorders [1, 56]. Dancey et al. reported the prevalence of apnea among women based on menopausal stages to be 47% in postmenopause, yet with a lower prevalence of 21% at the premenopause stage [33]. The study by Heinzer reported the prevalence of OSA at the postmenopause stage as 23%, and 9% at the premenopause stage, showing the higher prevalence of this disorder during postmenopause [56].

Several accelerating and persistent factors, including hormonal changes, menopausal symptoms, and mood disorders contribute to this disorder during menopause [57, 58]. Some studies reported chronic insomnia among 31 to 42% of women at the end of the perimenopause period [59]. A study conducted in China on 305 women reported that the prevalence of this disorder in perimenopause was 21%, which is more than in postmenopausal women with a prevalence of 14.7% [39]. Valiensi et al. reported that insomnia among postmenopausal women was 15% and Yang et al. reported that parasomnia was only 10% higher among the perimenopause population than postmenopause [60]. Based on a study in Brazil, insomnia in postmenopausal was 61.1%, yet this figure was reported at 55.9% among perimenopausal [18].

A study by Smith et al. showed that the incidence of insomnia at any stage of menopause could not predict the incidence of this disorder at other stages of menopause [61]. The most common sleep disorder in postmenopausal women is RLS at 63.8% [1, 62]. A study in Egypt reported the RLS, with incidences showing 87.9% among postmenopausal and 81% in premenopause [34]. In the present meta-analysis, parasomnia was most prevalent in the postmenopausal period, then in the perimenopause period, and the least prevalent in the premenopausal period. In general, the least common sleep disorder among postmenopausal was wakefulness disorder with a prevalence of 9% [16].

Conclusion

In view of the growing population of postmenopausal women, the importance of understanding the frequency and the effect of sleep disorders in this demographic group has taken on new urgency. Policymakers may use the results of the present meta-analysis to plan future healthcare, emphasizing the importance of sleep health education, treatment of sleep disorders, and improving the health of menopausal women as a research priority.