Scientists have been studying the effects of the moon on people’s sleep for years. Now, findings from a large study on human sleep published in the journal Science of the Total Environment seem to substantiate that the moon’s cycles do indeed affect our sleep patterns. But those effects are perceivably different for men and women, reports

For the inquiry, researchers observed the sleep patterns of more than 850 men and women in Uppsala, Sweden, on one night each year during different moon phases for over a period of several years. Scientists determined the onset, duration and quality of individuals’ sleep and noted any links between the assessed calculations and the moon’s cycles. (The periods when the silvery orb was brightly lit and those areas appeared larger in size are described as the moon waxing to full moon status versus when its radiance waned and its bright became diminished afterward.)

Results showed that the moon’s waxing and waning phases affected male and female participants differently.

“We found that men whose sleep was recorded during nights in the waxing period of the lunar cycle exhibited lower sleep efficiency and increased time awake after sleep onset compared to men whose sleep was measured during nights in the waning period,” said Christian Benedict, PhD, an associate professor in Uppsala University’s department of neuroscience and the study’s first author. “In contrast, the sleep of women remained largely unaffected by the lunar cycle.”

Specifically, researchers noticed that women clocked nearly 12 minutes less sleep on nights the moon was waxing compared with during the evenings it was waning. In comparison, men slept 20 minutes less than women on those nights that more of the moon’s surface area was aglow, and they slept worse on these nights, experiencing wakefulness and more interruptions during their sleep cycles.

Researchers cautioned that the findings show a correlation between the lunar cycles and sleep but not necessarily a cause-and-effect relationship.

Scientists explained that circadian rhythms controlling sleep timing and quality are also affected by cues other than light, including gravity.

“Differences in the moon’s gravitational pull at bedtime between the waxing and waning phases might, therefore, explain some of the observed differences in sleep,” concluded researchers.

To learn more about the health effects of sleep, read “When It Comes to Sleep, Quality Beats Quantity.”