# Sleep–wake changes and incident depressive symptoms in midlife women

## TL;DR

This study found that significant sleep-wake changes in midlife women are linked to a higher risk of developing depressive symptoms.

## Contribution

The study demonstrates a novel association between severe sleep-wake changes and increased risk of depressive symptoms in midlife women.

## Key findings

- Severe sleep midpoint changes were associated with a 51% higher risk of depressive symptoms compared to mild changes.
- The association remained significant after adjusting for multiple health and lifestyle factors.
- The study highlights the importance of stable sleep patterns in preventing depressive symptoms in midlife women.

## Abstract

Our study aimed to investigate the relationship between sleep–wake changes and depressive symptoms events among midlife women. We enrolled 1579 women aged 44–56 years who had no clinically relevant depressive symptoms at baseline. Depressive symptoms were assessed at each visit using the Center for Epidemiologic Studies Depression scale. At the third and fourth follow-up visits, women reported their sleep habits. The sleep midpoint was defined as the time to fall asleep plus one-half of the sleep duration. Sleep–wake changes were determined by the difference in the midpoint of sleep between the third and fourth visits, which were 1 year apart. The median follow-up time was 7 years (range 1–7 years). Cox proportional hazard models were fitted to calculate hazard ratios and 95% confidence intervals for the incidence of depressive symptoms associated with sleep–wake changes. After adjusting for potential confounding factors, the hazard ratio (95% confidence interval) of depressive symptoms for severe sleep midpoint changes was 1.51 (1.12, 2.05) compared with mild sleep midpoint changes. This relationship remained statistically significant and changed little when additionally controlling for sleep duration, sleep quality, insomnia symptoms, use of sleep medications, use of nervous medications, glucose, insulin, lipids, dietary energy intake, and C-reactive protein. Our findings indicate that exposure to long-term severe sleep–wake changes increases the risk of depressive symptoms in midlife women.