Does the Full Moon Affect Sleep and Mood? What Research Says

Ask a group of nurses, teachers or police officers and many will tell you that full moon nights are wilder. The word “lunatic” even comes from the Latin word for moon. But what does research actually say?

Sleep: some intriguing findings

A handful of studies have found small links between the lunar cycle and sleep. A 2013 laboratory study in Switzerland reported that volunteers took slightly longer to fall asleep and had a little less deep sleep around the full moon, even though they could not see the moon. A larger 2021 study that tracked people in both rural and city communities found that many went to bed later and slept less on the nights before a full moon. One explanation is simply extra evening moonlight, which our ancestors may have used to stay active later.

Other studies have not found these effects, and the differences reported are usually small, often a matter of minutes. Researchers agree that more work is needed.

Mood and behaviour: mostly myths

Many studies have looked for full moon effects on emergency room visits, crime, births and mental health admissions. Most have found no reliable link. The belief persists partly because of “confirmation bias”: a hectic shift during a full moon is memorable, while a hectic shift on an ordinary night is forgotten.

So should you track it?

If you are curious, keep a simple sleep and mood diary alongside the moon phase for a few months. You may notice a personal pattern, or you may find none. Either way, the habit of noticing your sleep is useful in itself. Our guide to tracking the lunar cycle shows you how.

If you have ongoing sleep problems or low mood, please speak to a doctor or qualified professional rather than relying on the moon.