Bedroom nighttime light exposure before and after sleep may promote pubertal progression in children and adolescents, whereas nighttime light exposure before waking may delay pubertal onset, and these associations differed by sex.
Light exposure at night in the 1 hour before waking was inversely associated with pubertal onset at baseline survey.
Each log-unit increase in nighttime light exposure 1 hour before sleep was associated with an 18% increased risk of pubertal progression.
Each log-unit increase in nighttime light exposure 1 hour after sleep was associated with a 14% increased risk of pubertal progression overall.
Among boys, higher nighttime light exposure 1 hour before waking was associated with an 18% lower risk of pubertal onset.
Among girls, higher nighttime light exposure 1 hour before waking was associated with a 17% lower risk of pubertal progression.
The study used a prospective design with objective light measurement across three distinct nighttime exposure windows.
This research suggests that the timing of light exposure in a child's bedroom at night matters for pubertal development. Using objective light measurements taken over four nights in Beijing children aged 6-14, the study found that light exposure around the time children go to sleep and just after falling asleep was associated with faster pubertal progression — meaning children advanced more quickly through puberty stages over a one-year follow-up period. In contrast, light present in the bedroom in the hour before waking up in the morning was associated with a lower likelihood of puberty having already started, suggesting a possible delaying effect on pubertal onset. The findings also differed by sex. In boys, pre-sleep and post-sleep light were each linked to faster pubertal progression (22% and 17% higher risk per log-unit increase, respectively), while pre-waking light was linked to an 18% lower risk of having started puberty. In girls, the pre-waking light was associated with a 17% lower risk of pubertal progression. These sex differences suggest that light at night may affect hormonal systems involved in puberty differently in boys and girls. This research suggests that the nighttime light environment in children's bedrooms may influence the timing of puberty, which has potential implications for health since early or altered pubertal timing has been linked to various health outcomes. The authors call for greater attention to healthy nighttime light environments for children as part of sexual health education, though further research is needed to confirm these findings and understand the biological mechanisms involved.
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Upload Your LabsShi D, Wang Y, Dang J, Liu Y, Chen Z, Liu J, et al.. (2026). [Association between light exposure at night and pubertal development in children and adolescents].. Zhonghua liu xing bing xue za zhi = Zhonghua liuxingbingxue zazhi. https://doi.org/10.3760/cma.j.cn112338-20251101-00782