--- title: Does the timing of the menstrual cycle relative to moon phases affect sleep quality? description: Women whose menstrual cycles began during the dark lunar period had worse sleep quality than those whose cycles began during the light lunar period. The effec url: https://niyora.com/research/papers/the-relationship-between-the-lunar-phase-menstrual-cycle-onset-and-subjective-2021/ --- - [Niyora](https://niyora.com/) - [Research](https://niyora.com/research/) - [Library](https://niyora.com/research/library/) - Does the timing of the menstrual cycle relative to moon phases affect sleep quality? Survey study, 2021 # Does the timing of the menstrual cycle relative to moon phases affect sleep quality? Women whose menstrual cycles began during the dark lunar period had worse sleep quality than those whose cycles began during the light lunar period. The effect was strongest when cycles began during the dark period in two consecutive months. Early or limited evidence 529 women aged 25-39 ## What they did 529 women aged 25-39 tracked their menstrual cycles using a smartphone app and reported their sleep quality. Researchers examined whether the timing of cycle onset matched light or dark lunar periods. ## What they found There was no overall connection between when the menstrual cycle started and the lunar phase. However, women whose cycles began during the light period had better sleep quality than those whose cycles began during the dark period. This effect was strongest in women whose cycles began during the dark period in two consecutive months or during periods of rapid lunar change. ## What it means for you Sleep quality may be worse when the menstrual cycle starts during a dark lunar period, particularly if this happens repeatedly. The mechanism is unclear and the study only measured association, not cause and effect. 529 women studied 6 menstrual cycles tracked per woman 25-39 age range in years ## About the study Original title The Relationship between the Lunar Phase, Menstrual Cycle Onset and Subjective Sleep Quality among Women of Reproductive Age Authors Komada Y, Sato M, Ikeda Y et al. Journal International journal of environmental research and public health Year 2021 Study design Survey study Participants 529 Open access Yes Read the paper [doi.org/10.3390/ijerph18063245](https://doi.org/10.3390/ijerph18063245) Original abstract The aim of the present study was to investigate the association among lunar cycle, menstrual cycle onset, and subjective sleep quality. Menstrual cycle onset data from the six most recent menstrual cycles were obtained for 529 women (aged 25-39 years) using the smartphone app Luna Luna. We also collected questionnaire survey data on sleep quality from each participant. Overall, there was no association between the onset of menstrual cycle and lunar phase. Interestingly, the proportion of good sleepers with menstrual cycle beginning during the light period was significantly higher than that during the dark period, while the proportion of poor sleepers with menstrual cycle beginning during the dark period was significantly higher than that during the light period. When participants were categorized by the combination of lunar phases (light, dark, neutral periods) in the two most recent menstrual cycle onsets, the "both dark period" group and the "other (light and dark) period" group showed the lowest proportion of good sleepers. Menstrual cycle onset in the dark period was associated with a deterioration in subsequent subjective sleep quality, which was more apparent with consecutive onsets in the dark period or at a rapidly changing lunar phase. Reproduced under CC-BY. ## Topics [Sleep and insomnia](https://niyora.com/research/topics/symptom-sleep/)[Apps and digital interventions](https://niyora.com/research/topics/treatment-digital-health/)[Work and productivity](https://niyora.com/research/topics/life-area-work/)[Relationships and partners](https://niyora.com/research/topics/life-area-relationships/) Research tells you what helps on average. Niyora helps on the day it hits. Calm down, see it another way, and decide what to say, with a PMS and PMDD app built by a doctor. ## Related studies Cohort study, 2026 Does sleeping longer improve mood and fitness in elite athletes? Survey study, 2026 How does sleep change across the menstrual cycle in women with psychiatric conditions and suicidal thinking? Survey study, 2026 How do pain, sleep quality, and appetite change across the menstrual cycle? Study, 2024 How do finger temperature, heart rate, and sleep change across the menstrual cycle? Cohort study, 2024 Does shift work worsen PMS symptoms in newly graduated nurses? Lab study, 2023 Does sleep change across the menstrual cycle? Ask AI about this page Copy prompt ChatGPT ↗ Claude ↗ Perplexity ↗ Google AI Mode ↗ Grok ↗