The Moon’s Effect on Sleep

Humans have a love affair with the moon. And rightly so. This beautiful celestial body has been the subject of fascination from ancient times—in mythology and folklore—to present day science. Now, we seem to know it all: its size, surface area, rotation time, approximate age, its gravitational pull on the ocean. We spend billions of dollars to touch it, to walk on it.

And yet, when it comes to the moon’s effect on human biology and behavior, there remains a great deal of mystery—a subject still immersed in unproven antidotes and mysticism.

It has long been said that the full moon evokes an energy that can tip an unstable person into insanity (hence the word lunatic), cause some people to become violent, or make epileptics more likely to have seizures. Many police officers and emergency room workers confirm this. And yet, most scientific studies have failed to establish a link between the moon’s cycle and human behavior.

Now, however, there is an exception: sleep. In a regular sleep study conducted back in 2000, Swiss scientists recorded participants’ sleeping habits over a three-year period. The researchers analyzed subjects’ brain waves with an electroencephalogram (EEG), measured their levels of melatonin, and timed how long it took them to fall asleep and remain in deep sleep. Then they asked participants how refreshed they felt the next day.

It wasn’t until a decade later that the researchers wondered if the moon might have had an effect on the results. So they went back and analyzed the sleeping data according to the phases of the moon. It turns out that the moon had a significant effect.

The findings, published in the journal Current Biology, were undeniable. During the three or four nights surrounding a full moon, participants spent 30% less time in deep sleep, slept an average of 20 fewer minutes each night, and it took them five minutes longer to actually fall asleep. They also had lower levels of melatonin and felt less refreshed the next morning compared to other days of the month.

Perhaps one day science will be able to unravel more of the moon’s unexplainable effects on human behavior. Perhaps not. But for now, we are content to let the moon have its secrets, to remain a beautiful mystery.