# Light at night exposure and risk of depression: a meta-analysis of observational studies

## TL;DR

Exposure to light at night is linked to a higher risk of depression, according to a meta-analysis of observational studies.

## Contribution

This study provides a comprehensive meta-analysis confirming the association between light at night and depression risk.

## Key findings

- Higher LAN exposure is associated with a 22.4% increased odds of depression (OR = 1.224).
- The association varies by exposure type, age, sample size, and geographical region.
- Moderate to high heterogeneity suggests the need for higher-quality studies.

## Abstract

Depression is a common mental disorder, and emerging evidence suggests a link between light at night (LAN) exposure and increased risk. This meta-analysis systematically synthesises the accumulating evidence on the LAN-depression relationship.

We systematically examined PubMed, Web of Science, Embase, Cochrane Library, CNKI and Weipu databases up to June 2025, following PRISMA guidelines. The combined effect size was calculated based on a random-effects model. Heterogeneity among studies was assessed through Cochran's Q test and I2 statistic. Subgroup analyses were performed on types of LAN exposure, participant age categories, sample size, LAN exposure assessment and geographical regions. The study was registered on the international prospective register of systematic reviews (PROSPERO ID# CRD420251120552).

We included eight studies published from 2013–2025. Individuals with higher exposure to LAN had higher odds of depression (odds ratio (OR) = 1.224; 95% confidence interval (CI) = 1.176–1.275). Subgroup analyses revealed that the association varied by LAN exposure types, participant age categories, sample size, LAN exposure assessment and geographical regions.

s Our research confirms a significant association between LAN exposure and elevated depression risk. Moderate to high heterogeneity and low sample sizes warrant higher-quality studies to help guide decisions to mitigate nocturnal light pollution and its psychological impacts.