Yes, the moon can really affect your sleep

You’ve gone to bed on time as usual, ditched the afternoon coffee, and made your room cool, dark, and quiet; Exactly as the experts recommend. However, you still toss and turn in bed and can’t sleep. Then you see a silver light entering the room through the curtains. The moon is full. Could this be the cause of your insomnia?

The challenge of studying the effect of the moon on sleep

Examining the relationship between the moon and human sleep is not so simple. On the one hand, many people have strong beliefs about the effect of the full moon on their mood.

“Many people find it romantic to see a full moon, especially on occasions like a harvest moon or a blue moon,” says Stephen Carstensen, an expert on sleep-related breathing disorders. “Perhaps its effects come more from emotions than from the body’s physiology.”

When someone believes that he will not sleep on the night of the full moon, this expectation can keep him awake. However, scientific evidence suggests that the moon may have a real effect on sleep.

Scientific findings

In a 2013 study in Switzerland, experimental data were examined in which participants were unaware of the study of the relationship between sleep and the moon cycle. The results showed that during the full moon, the brain activity in the deep sleep phase decreased by about 30%, the time to fall asleep increased by five minutes on average, and the participants slept about 20 minutes less. They also reported poorer sleep quality and lower levels of melatonin—a hormone your body naturally releases at night to prepare you for restful sleep.

“We know that light, both artificial and natural, can suppress the release of melatonin, so it makes sense that moonlight also has a natural effect on keeping the body awake,” says Alex Dimitriou, MD, a psychiatrist and sleep medicine specialist and founder of the Menlo Park Psychiatry and Sleep Medicine Center.

In another study on 47 healthy people, similar results were obtained: the participants slept about 25 minutes less on nights close to the full moon. Interestingly, men were more affected than women and slept about 50 minutes less in total. It was also found that it takes about 30 minutes longer to reach the stage of REM sleep (the stage of dreaming).

But a later research in Hungary had a different result and showed that women have more sleep disorders than men on full moon nights.

However, all these studies have a fundamental limitation: they were conducted in a laboratory setting, where the unfamiliar environment itself can alter sleep quality.

Research in the real world

To solve this problem, a group of scientists from the University of Washington took their study to the real world. They studied the sleep of people in three different areas of Argentina: one on the outskirts of the city, another in a village with limited access to electricity, and a third in a remote area without electricity. Also, the data of 464 students of Seattle University were analyzed. All participants wore a wristband that recorded their sleep for two months.

In all groups, regardless of access to artificial light, people fell asleep later and slept less on the nights leading up to the full moon. The researchers believe this pattern could reflect an ancient adaptation: When the moon shines brighter, our ancestors likely stayed awake longer to hunt, talk or work in natural light.

These changes in sleep were more pronounced in communities with little access to electricity, where moonlight was still the main source of nighttime illumination. By contrast, in urban communities, according to Carstensen, the effect of artificial light on sleep is much greater than that of moonlight.

Dimitriou also agrees with him: “The moon’s ability to reduce sleep time by about an hour is really remarkable. “If a full moon can have such an effect, imagine how much more a bright screen light can have, right in front of your eyes.”