# A U-shaped relationship between nighttime sleep duration and new-onset emotional, nervous, or psychiatric problems: a prospective cohort study from China

## TL;DR

The study found that both too little and too much nighttime sleep are linked to a higher risk of new emotional or psychiatric problems in a Chinese population.

## Contribution

This study identifies a U-shaped relationship between nighttime sleep duration and new-onset emotional, nervous, or psychiatric problems.

## Key findings

- A U-shaped relationship was found between nighttime sleep duration and new-onset emotional, nervous, or psychiatric problems.
- The lowest risk of these problems was observed at a nighttime sleep duration of 6.5 hours.
- BMI, hypertension, and diabetes did not significantly mediate the association between sleep duration and new-onset problems.

## Abstract

Sleep plays an important role in maintaining physical and mental health, and it is important to study the relationship between sleep duration and new-onset emotional, nervous, or psychiatric problems (ENP).

A prospective cohort study was performed based on data from Wave 2011, 2013,2015 and 2018 in the China Health and Retirement Longitudinal Study (CHARLS) databases. Sleep duration was assessed by self-reported nighttime sleep and daytime nap duration. Self-reported diagnoses were used to identify the new-onset emotional, nervous, or psychiatric problems (ENP). We used different logistic regression models to explore the potential effects of sleep duration on ENP and performed mediation analyses to assess the mediating roles of BMI, hypertension, and diabetes(DM).

Among 10,225 participants, 221 (2.16%) developed ENP during follow-up. The mean nighttime sleep duration was significantly shorter in the ENP group than in the non-ENP group. A restricted cubic spline regression model revealed a U-shaped relationship between nighttime sleep duration and ENP risk, with the lowest risk at 6.5 hours. Mediation analyses showed that BMI, hypertension, and diabetes did not significantly mediate this association (P values for ACME were all greater than 0.05).

A U-shaped association was observed between nighttime sleep duration and new-onset ENP, suggesting that both insufficient and excessive sleep may increase the risk of ENP. These findings highlight the importance of maintaining an optimal sleep duration for mental well-being.