Association Between Obesity and Sleep Disorders in Postmenopausal Women

Maria Fernanda Naufel, MSc; Cristina Frange, MSc; Monica Levy Andersen, PhD; Manoel João Batista Castello Girão, MD, PhD; Sergio Tufik, MD, PhD; Eliane Beraldi Ribeiro, PhD; Helena Hachul, MD, PhD

Disclosures

Menopause. 2018;25(2):139-144. 

In This Article

Discussion

The present investigation compared sleep architecture of obese and nonobese (BMI <30.0 kg/m2) postmenopausal women to ascertain whether anthropometric data influenced sleep disorders. Concerning body composition data, we found that most of the nonobese participants were overweight and had WC and WHR values above the cut-off points for women, as determined by the World Health Organization (<80.0 cm and <0.85, respectively).[25] These observations agree with data showing increased fat mass and a high prevalence of abdominal fat deposition in the postmenopausal population.[26–28]

The prevalence of obesity in postmenopausal women is high and increasing worldwide, with up to 30% or more being obese.[29–31] A recent study of Brazilian women found a high frequency of obesity among postmenopausal women (30%),[32] whereas a study from São Paulo city (Brazil) found a high prevalence of abdominal obesity.[19] Although our study is not representative of the whole country (Brazil), the data from this study are, nevertheless, similar to Brazil and worldwide postmenopausal women.

Although both groups had WC above the cut-off points, the obese group presented with a significantly higher WC than the nonobese group. Abdominal fat is closely associated with metabolic diseases such as insulin resistance, type 2 diabetes, and metabolic syndrome.[16,17] Moreover, abdominal obesity has been shown to positively correlate with sleep disorders in the obese population.[33–36] In postmenopausal women, an association between sleep disorders and body composition parameters has also been demonstrated. However, in the majority of these studies, sleep disturbances were assessed on the basis of self-report.[9,22,37]

Examining sleep architecture in postmenopausal women, we have previously shown that the OSA syndrome correlated with WC and BMI.[19,20] The present findings of increased AHI and RID in the obese group corroborate our previous results.[19,20] OSA is associated with several adverse health outcomes, such as excessive daytime sleepiness, cognitive, immune, cardiovascular impairment, and diabetes, leading to increased morbidity and mortality rates.[38–41]

Polysomnography records are scored using accepted waveform analysis conventions to reveal not only sleep or wake times and sleep indicators, but also the type and duration of sleep stages and neural arousals or perturbations.[23,24] Thus, we performed the present study to extend our previous observations to all PSG parameters, to better understand the effects of obesity on sleep architecture.

Rapid eye movement sleep time was lower than ideal values in both groups, whereas stage N1 NREM sleep was increased, suggesting that, independent of BMI, postmenopausal women spent more time in light sleep. These findings showed altered objective sleep pattern, indicative of impaired sleep quality. We found that LREM was positively correlated with body mass, BMI, and hip circumference, showing that obesity is associated with difficulty to reach REM sleep. We also found that WHR was negatively associated with sleep efficiency, whereas WC and WHR were positively correlated with WASO, indicating that central fat is related to the increase in sleep fragmentation and poor sleep quality in postmenopausal women.

It is important to point out that, due to its cross-sectional design, the present study does not allow for the assessment of temporality. Another limitation of our study was the absence of questions regarding alcohol or caffeine intake, drug use, diet, and history of psychiatric disorders. All of these covariates are known to be associated with sleep disorders such as sleeplessness, decreased total sleep time, difficulty falling asleep, increased nocturnal awakenings, and daytime tiredness.[42–45]

Despite these limitations, our study is, to the best of our knowledge, the first one to investigate the influence of obesity in LREM in postmenopausal women. The linear regression model showed that BMI and WHR were positive predictors of LREM. Since LREM is the duration of sleep from sleep onset to the onset of the first stage REM sleep period, it can be stated that weight gain and abdominal obesity make it more difficult for postmenopausal women to enter REM sleep stage. It is reasonable to suggest that the low percentage of REM sleep time observed in both the obese and the nonobese groups was influenced by their increased mean BMI and WHR values.

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