Does the moon actually influence human health?

For starters, using activity-monitoring wrist watches to track sleep patterns in two very different populations, the team found that members of Indigenous communities in rural Argentina – many of which do not use electricity – slept less overall on nights leading up to the full moon.

 

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What wasn’t anticipated was that the hundreds of University of Washington undergraduate students who also took part would experience the same thing in a large city where artificial light drowns out moonlight. But they did.

And many subjects in both groups additionally slept less around the new moon, the lunar phase during which the moon generally isn’t visible.

Moreover, these moon-related fluctuations in sleep patterns are posited to be responsible for the cycle back and forth between depression and mania that’s common amongst people with bipolar disorder, given sleep deficits play a significant role in triggering this.

‘In many cases, I think we could capitalise on this knowledge to prevent some symptoms of disease that are highly dependent on how much sleep you have,’ says sleep researcher Horacio de la Iglesia.

In terms of periods, evidence shows that the female menstrual cycle – which lasts 28 days on average – can match with lunar cycles in some women.

As the participants aged and became more exposed to artificial light at night, their cycles shortened and the synchrony disappeared.

It’s thought that although women’s cycles once harmonised with the moon, modern life has taken its toll, but further investigations will be necessary to confirm this.

‘There is a lot of work ahead of us, and we hope that our colleagues embark with us of what could be a future area of circadian medicine,’ says paper author, Dr Claude Gronfier.