Researchers have been investigating how the lunar cycle is impacting quality of sleep – their findings may offer some insights

restonic moon greyEven in ancient times, the phases of the moon were believed to affect human behaviors. A full moon has often been cited as the cause for everything from sleepwalking to illegal activity. The association is so close that the words, “lunatic” and “lunacy” come from the Luna, the name of the Roman goddess of the moon, said to ride her silver chariot across the sky every night. Even Hippocrates, the father of modern medicine, noted the ties between mania and the moon. Beliefs endured throughout the centuries. People on trial in 18th-century England often received lighter sentences if their crimes occurred during a full moon.

What does science say about the moon – and our relationship to it?

Can’t sleep? Blame it on the Full Moon! Modern researchers have and studied it in-depth, especially when it comes to the impact of the moon phases on sleep. It might help explain why you experience disturbances in your sleep cycles and how quality of rest is affected. A study published in 2021 indicates that our natural circadian rhythms are synchronized with phases of the lunar cycle (29.5 days long). It found people often go to bed later and sleep less leading up to a full moon. The biggest swings happened 3-5  days before.

The total amount of sleep varied across the lunar cycle by an average of 46-58 minutes, and bedtimes seesawed by approx. 30 minutes. Although those aren’t huge variations, they’re enough for some people to feel out of sorts. Just how much a one hour shift for Daylight Savings Time affects people is well documented. The changing of the clocks has been shown to be linked with a 6% increase in motor vehicle accidents caused by an impairment of focus and judgment.

Why is our sleep affected by the moon?

One researcher has a theory. “We hypothesize that the patterns we observed are an innate adaptation that allowed our ancestors to take advantage of this natural source of evening light that occurred at a specific time during the lunar cycle,” said lead author Leandro Casiraghi, a University of Washington postdoctoral researcher in the department of biology.

An earlier sleep study from 2013 also found that the full moon negatively impacted sleep. Data showed that participants took five minutes longer to fall asleep, slept for 20 minutes less and took longer to reach REM sleep. Perhaps most significant impact was  a 30% reduction in deep sleep. That’s the type of sleep crucial for good brain health, including learning, and the creation and storage of memories.

There’s also research that showed when sleep time was reduced by 25 minutes there was increased frequency of nighttime arousals and awakenings. It may be tempting to blame artificial light but researchers compared the sleep patterns of indigenous Argentinian communities and urban dwelling American college students. Both groups experienced the same type of sleep disruptions, falling asleep later and sleeping less for a week before the arrival of the full moon.

How much you’re impacted by the moon may depend on your gender

Can’t sleep? Blame it on the Full Moon! One study showed that men slept 21 minutes less, while for women, it was 12 minutes less on waxing nights (ones where the moon is getting bigger each night). Previous research showed men had lower melatonin and testosterone levels during full moons. In addition, they had higher levels of cortisol, the stress hormone. It may be something that romantic partners might want to note when planning intimate time.

There are some scientists who aren’t totally convinced about how much the lunar cycle interferes with sleep though. But it’s clear there’s enough evidence to warrant further investigation. As researcher Casiraghi says: “In general, there has been a lot of suspicion about the idea that the phases of the moon could affect behaviors, such as sleep — even though in urban settings with high amounts of light pollution, you may not know what the moon phase is unless you go outside or look out the window. Future research should focus on how is it acting through our innate circadian clock? Or other signals that affect the timing of sleep? There is a lot to understand about this effect.”

In the meantime, as science continues to evolve and reach a consensus, what’s the sensitive sleeper to do to battle havoc brought on by lunar cycles? In the three to five days before a full moon, it’s a good idea to fine-tune all of your good sleep behaviors. A few you’ll definitely want to embrace include:

And if you’re still feeling moonstruck and sleep deprived? Go ahead and take a short nap. About 20 minutes is ideal.

Rest well & wake up ready to go!

Better sleep gives rise to better mornings, bringing your goals into focus and dreams within reach. Hungry for more sleep info? Dig into these posts:

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This blog does not provide medical advice. It is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional medical advice, diagnosis or treatment and should not be relied on to make decisions about your health. Never ignore professional medical advice in seeking treatment because of something you have read on If you think you may have a medical emergency, immediately call your doctor or dial 911.

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