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Can the Moon Actually Affect Your Sleep?

There's a full harvest moon Friday September 16. We dug through research to see whether it'll influence your shut-eye.

The end of summer and start of fall is marked by a Harvest Moon—the full moon that falls (or, rather, rises) closest to the autumnal equinox, September 22. That Harvest Moon will peak at 3:05pm Eastern Daylight Time on Friday, September 16th, according to (You can also check out the lunar eclipse happening simultaneously; you won’t be able to see it in the States, but you can watch it from a live webcast here, at 

Now, werewolf jokes aside, there's been some debate over the moon's ability to sway and throw off our sleep patterns.  

A University of Basel in Switzerland study in the journal Current Biology suggests people tend to get lower-quality sleep around the time of full moons, losing about 20 minutes of sleep compared to what they get during a new moon.

The researchers brought 33 healthy men and women between the ages 20 and 74 into a sleep lab. The participants slept under controlled conditions while an EEG assessed their brain waves and sleep; aside from the humidity and temperature being controlled, there were no windows, so they had no way of seeing the moon or light. They stayed in the lab for a little over three days. 

When looking at sleep quality, total sleep time, and the time it took to fall asleep, the results are pretty interesting. The full moon was associated with a 30 percent decrease in deep sleep duration, a 20-minute reduction in total sleep time, and a delay in sleep latency of about five minutes. On the days leading up to the full moon, men and women both had lower evening levels of melatonin—the sleep hormone responsible for keeping your circadian rhythm regular and kickstarting your body's day and night cycles. It makes you think: Why does the moon influence melatonin? 

While researchers aren’t really sure how or why the moon has an affect on melatonin, it’s likely due to how we've evolved over time. (For example, women’s bodies are synchronized to the moon through their menstrual cycle.) Our internal clocks are thought to be located in a nucleus within our brain, which controls the production of melatonin, according to the National Institute of General Medical Sciences. So it’s very possible our bodies are running in time with space in a different sort of space race—one where we're constantly trying to keep up with the cosmos.

The researchers also cite a field study published in the Journal of Sleep Research in which 31 participants kept daily sleep logs over 6 weeks; researchers found people slept about 19 minutes less on nights with a full moon compared with a new moon—findings that nearly mirror the Current Biology study that clocked a 20-minute reduction.

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"While lunar cycles have been much celebrated in different cultures, and despite the persistent belief that our sleep is affected by the phases of the moon, so far there has been no reliable quantitative evidence that the moon can influence cortical activity during sleep," the University of Basel in Switzerland researchers say in their research. "Thus, we have evidence that the distance to the nearest full-moon phase significantly influences human sleep and evening melatonin levels when measured under strictly controlled laboratory conditions, where factors such as light and personal moon perception can be excluded."

Likewise, further research published in Sleep Medicine found a full moon is associated with lower sleep efficiency. In the cross-sectional analysis, data from 319 patients was analyzed by a polysomnography, a sleep test that tracks your brain waves, blood oxygen levels, heart rate, breathing, and eye and leg movements. Of all participants, 224 persons had their sleep study done during an alternate moon (i.e. crescent), 47 during a full moon, and 48 during a new moon. 

On the flip side, research published in Sleep Journal found no difference between lunar phases when it came to self-reported sleep quality, polysomnographic parameters (noted above), and difference in cortisol levels. In this study, a total of 2,125 men and women evaluated their sleep using a self-rating scale, 759 underwent a sleep EEG analysis while they slept, and all checked cortisol levels in saliva 30 minutes upon waking, then again at 11 a.m., and at 8p.m. Researchers found a small trend toward better sleep quality during the new moon phase and a slight trend toward shorter total sleep time during full moon—but not enough to say the moon has a significant effect. 

Not sure what to make of the research? Do a little experiment yourself. Look at the data from your tracker and see if you notice any trends in your sleep patterns around the phases of the moon. And if all else fails, just take a nap to make up for the missed shuteyes; there are plenty of benefits to taking a quick snooze. Speak to your doctor about whether taking melatonin supplements might help. You can also try: 

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