Nocturnal light pollution and clinical signs of ovulation disorders

Objective: Assess quantitatively the impact of nocturnal light pollution on the menstrual cycle. Design: Cross-sectional observational study. Setting: Single French institute from November 2017 to March 2018. Participants: Nineteen ostensibly healthy menstruating women aged 19 to 45, inclusive Intervention(s): None Main outcome measures: Assessment of nocturnal light pollution (questionnaire and lux meter) and 22 clinical signs of ovulation disorder. Wilcoxon tests were used to quantify the abilities of nocturnal light pollution factors to predict clinical signs of ovulation disorders. Results: Nearly half of the 94 daily observations made by questionnaire and measurements made by lux meter indicated light pollution due to light flooding into the bedroom from indoor or outdoor sources. Nearly more than half of the 56 menstrual cycles presented at least mild abnormalities. The data showed that some clinical signs of ovulation disorders may be significantly predicted by factors of light pollution but a lack of power prevented reaching Bonferroni criterion. Conclusions: The indications of negative impact of dim light at night on some menstrual cycle characteristics call for a randomized study to quantify improvements of menstrual cycle characteristics brought by suppressing nocturnal light pollution. This will pave the way for new therapeutic perspectives for some difficult cases of ovulation disorders.