Nocturnal Hot Flashes, but Not Serum Hormone Concentrations, as a Predictor of Insomnia in Menopausal Women: Results from the Midlife Women's Health Study

Background: Sleep disruptions are among the most common symptoms experienced during menopause and can be associated with depression, hot flashes, and fluctuating hormones. However, few studies have examined how such risk factors influence sleep in midlife women in a network-based approach that will establish the complex relationship between variables. Materials and Methods: We used a Bayesian network (BN) to examine the relationship between multiple factors known to influence sleep and depression in midlife women, including hormone concentrations, hot flashes, and menopause status among participants of the longitudinal Midlife Women's Health Study. In year 1, 762 women (45-54 years of age) answered questions regarding the frequency of insomnia, hot flashes, and depression; 389 of the same women answered similar questions at year 4. We measured serum hormones and calculated free estradiol index, free testosterone index, and ratios of estradiol:progesterone, and estradiol:testosterone. For our model, we calculated the change in frequency of insomnia, depression, and covariates (body mass index, menopause status, hot flashes at night, and present quality of life) from year 1 to 4. Results: Using a BN, we found that self-reported hot flashes at night, and no other factors, were direct predictors of self-reported insomnia in year 1. Surprisingly, we did not identify an association between hormone concentrations and self-reported insomnia. Frequency of insomnia in year 4 was only predicted by frequency of insomnia in year 1, whereas frequency of depression in year 4 was predicted by year 4 insomnia and frequency of depression in year 1. No other factors were direct predictors of insomnia or depression in our model. Conclusions: Therefore, hot flashes at night, previous insomnia, and depression are stronger predictors of how women will self-report frequency of sleep disruptions and treatment may reduce menopausal sleep complaints.