Does a full moon affect sleep? We investigate

Full moon in a dark night sky
(Image credit: Ganapathy Kumar on Unsplash)

Anecdotally, plenty of people experience disrupted sleep on nights around a full moon. But why might this be, and is there any science to back it up? October's full moon falls on the night of Sunday 9 October, and is known as the Hunter's Moon. If widespread theories are to be trusted, that means your sleep has probably already started to deteriorate. 

Below, we'll dig into exactly how and why a full moon might affect sleep, and offer some advice on how to avoid a sleepless night on Sunday (or any full moon). For more tips, head to our guide to how to sleep better at night naturally, or check out our best mattress guide if it's time to upgrade your sleep setup.

Does a full moon affect sleep?

Many people believe that a full moon affects their physical and mental wellbeing, including having a negative impact on their sleep. Claims that the full moon might affect mental health (the word 'lunatic' stems from the belief that the lunar cycles caused changes in mental state) or make you physically ill don't have much by way of scientific backing, but there are multiple studies that suggest they can indeed distrust sleep. 

A large-scale study from 2021 (opens in new tab) focused on the sleep patterns in three indigenous Argentinian communities and 464 American college students in a big city. It found that all groups of participants fell asleep later and slept for less time overall in the week running up to a full moon. 

Person asleep in bed with the light falling across their face

(Image credit: Getty)

This 2013 study (opens in new tab) found that around the full moon, the time it took for participants' to fall asleep increased by five minutes, and sleep duration decreased by 20 minutes. There was a 30% drop in deep sleep, and participants reported worse sleep quality, too. This research from 2021 (opens in new tab) had similar findings, with participants tending to fall asleep later and sleep for a shorter period overall on the nights leading up to a full moon. 

One 2015 study (opens in new tab) of 205 adults found that there was a split based on gender. On nights close to a full moon, total sleep time, Stage 4 sleep and REM sleep were reduced in women, whereas in men the amount of REM sleep increased during that period.

While there's plenty of evidence to suggest there is a link between sleep quality / duration and lunar cycles, not all scientists agree. This 2015 study of 2125 people included both subjective and objective monitoring, and concluded there was no significant effect between lunar phases and sleep.

Why does the full moon affect sleep?

There are a few theories as to why a full moon might have a negative impact on sleep. One popular one is that it's to do with the increased amount of moonlight (that was the conclusion of the large-scale 2021 study mentioned above). Moonlight is sunlight bounced off the moon's surface and reflected back to Earth – albeit much more weakly. Because we know that our sleep-wake cycles are stimulated by rising and falling hormone levels in response to light, it makes sense that this could cause disrupted sleep. 

woman lying in bed with her hands over her face

(Image credit: Getty)

"As the moon passes through the four phases of its cycle, more light is reflected by the moon; at its fullest, making a good night's sleep can be challenging, explains psychologist and sleep scientist Theresa Schnorbach, who's the resident Sleep Expert at Emma (opens in new tab). "The difficulty comes from the fact that levels of light from the moon are brightest when it is at the full stage of its cycle. It is this bright, blue-toned light that impedes melatonin production, a hormone that signals to our body that it's time to sleep, and increases levels of cortisol, also known as a 'stress hormone', which keeps you awake."

The theory has some flaws, though. For instance, it's irrelevant if the weather is cloudy. Many studies – like this 2015 one (opens in new tab) – take place in a sleep lab with no windows. If you're in a city, artificial light will be much more prevalent than moonlight, too. 

Other theories suggest that it's to do with the moon’s gravitational pull (although this seems unlikely (opens in new tab)), or that it could be related to the moon causing electromagnetic fluctuations on Earth, to which humans may be sensitive. 

How to sleep better on a full moon

Whatever the cause, if you're concerned about your sleep quality in the run up to the new moon, here are some steps you can take to help improve your sleep quality.

Avoid blue light 

"Much like the bright light of the full moon, the blue light of tech will disrupt your melatonin production and your circadian rhythm, making it more difficult to fall asleep," says Theresa, She suggests minimizing your exposure to blue light by setting devices to 'night mode', or ideally avoiding devices entirely for a few hours before bed. 

Change you smart bulbs to warm colors

"While blue light works to stimulate your brain and keep you up, red light can work in the opposite way to aid sleep," explains Theresa. If you have smart bulbs, changing the tone to a warmer shade – or even making them red – before bed could improve your sleep.

Keep the heating off

The October Hunter's Moon is traditionally considered a marker of the descent into winter, and temperatures are certainly starting to drop. Theresa says we should resist reaching for the thermostat. "Turning the heating on can actually be counterproductive to sleep," she says. "The optimal bedroom temperature has actually been found to be around 15.5-19°C [around 41-66F]. This is because an integral part of winding down for sleep is your body cooling down."

Making sure you've got the right sleep setup can be important here – our guide to the best cooling mattresses runs down options that are specifically designed not to trap body heat. 

Ruth Hamilton
Sleep Editor

Sleep expert Ruth is your go-to person for all things snooze-related. She's currently on secondment in the Sleep Editor role (covering for Claire Davies), using everything she learned as T3's Wellness Editor to help recommend you the best products to help you get an amazing night's sleep. She has tested more mattresses than her small flat can handle and will talk at length about them to anyone who shows even a passing interest, and has had to implement a one-in-one-out pillow policy for fear of getting smothered by them in the night. As well as following all the industry trends and advancements in the mattress and bedding world, she regularly speaks to certified sleep experts to delve into the science behind a great night's sleep, and offer you advice to help you get there.