Effect of the Moon
Sleep
Debated
Some studies find shorter sleep near full moon, others nothing.
The evidence
A 2013 lab study re-analysed after the fact reported less deep sleep near full moon. Later studies disagree: one large dataset found nothing, another found shorter sleep, and 205 people showed no main effect. In 2021, wrist actimetry in Argentina and Seattle showed later and shorter sleep on the nights before full moon.
Key studies
- Evidence that the Lunar Cycle Influences Human Sleep Reported less deep sleep and shorter sleep near full moon, without moonlight in the room.
- Lunar cycle effects on sleep and the file drawer problem Found nothing, and pointed to the file-drawer problem: null results stay unpublished.
- Human sleep and cortical reactivity are influenced by lunar phase Found sleep and brain reactivity changing with the phase, supporting the effect.
- Reply to Cordi et al. Defends the 2013 finding; the exchange shows why one study is not enough.
- Effects of lunar phase on sleep in men and women in Surrey No main effect of the Moon on any sleep measure, only differences between men and women.
- Moonstruck sleep: Synchronization of human sleep with the moon cycle under field conditions Sleep started later and was shorter on the nights before full moon, in the countryside as in the city.