Before electric lights, the Moon played an important role in sleep cycles. On the nights before and around the full Moon, the moonlight let people spend more time working in the fields or doing other chores. Or the light shining through the window just made it harder to drift off. So people often fell asleep a little later and slept a little less.

And a recent study found that the same thing may still be going on today. Subjects went to bed later when there was a bright Moon in the evening sky, and slept a little less — even if they spent their evenings indoors, under artificial lighting.

Researchers used wrist monitors to track the sleep habits of people in three villages in Argentina. One village had no electricity, but the other two did. The scientists then looked at a similar study of almost 500 college students at the University of Washington.

And they found similar results. When the Moon was full or getting close to full, the subjects went to bed later. But they got up at about the same time no matter the phase of the Moon, so they got less sleep.

The researchers don’t know why the sleep cycles were so well synched with the phases of the Moon, though — leaving the subject unsolved.

The Moon will be full early Wednesday, so it’s nice and bright right now, and is in view all evening. The bright star Spica stands to the lower left of the Moon this evening, and will be closer to the right of the Moon tomorrow.

Script by Damond Benningfield

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