Does the Full Moon Really Affect Your Sleep?

Do you sleep worse when the moon is full, or does it only feel that way? Here is what the key studies found, where they disagree, and a simple test you can run on your own nights.

In this article

1. Does the full moon affect sleep?
2. What did the 2013 full moon study actually find?
3. Did later studies confirm the full moon effect?
4. Can bright moonlight in the bedroom disturb sleep?
5. Why does believing in the moon effect colour how nights are reported?
6. How can you check your own full moon and sleep pattern?
7. When should poor sleep be checked by a clinician?
8. Frequently asked questions
9. Final thoughts
10. Sources and further reading

Does the full moon affect sleep?

The full moon may affect sleep slightly in some people, but research has not established that it does. Full moon and sleep studies disagree: one small lab study found changes, while several larger analyses found no clear effect. The question is still open, with larger evidence leaning towards little or no effect.

If you are curious about unexplained poor nights more generally, why you wake up at 3 am covers the more common causes.

A bright full moon is easy to notice, so a poor night that coincides with one gets blamed on it. That is a story about attention, not evidence.

What did the 2013 full moon study actually find?

The 2013 study by Cajochen and colleagues in Current Biology reported that, around the full moon, 33 volunteers had less deep sleep, took longer to fall asleep, slept less and had lower melatonin. It was widely described as the first reliable evidence of a lunar rhythm in human sleep. It was widely reported as the first reliable evidence of a lunar rhythm in human sleep under controlled laboratory conditions.

The reported numbers

According to the study summary, volunteers in two age groups slept in a windowless laboratory with no time cues. Around the full moon, deep-sleep brain activity fell by about 30%, volunteers took about five minutes longer to fall asleep, slept about 20 minutes less, and had lower melatonin. They also rated their sleep as poorer.

Why it needs caution

The authors analysed the data retrospectively: the recordings existed already, and the lunar question was asked afterwards. That is weaker than a study designed to test the moon from the start. The sample was also small.

Did later studies confirm the full moon effect?

Later studies largely did not confirm a full moon effect on sleep. A 2014 re-analysis of 1,265 volunteers, a 2015 population study of 2,125 people and a 2015 lab dataset of 205 people found no clear overall effect, though results were not perfectly uniform. Larger samples generally pointed to a null or very small result.

Moonlight is only one of many things that change how people sleep in a new setting, as why you sleep badly the first night in a new place shows.

The 2014 re-analysis and the file drawer problem

Cordi and colleagues, also in Current Biology, found no statistically relevant correlation between sleep and lunar phase. They also reported unpublished null findings, including cumulative analyses of more than 20,000 sleep nights, and suggested publication bias (the "file drawer problem") may explain why positive results reach print more easily. They too used retrospective data, and called for controlled studies designed to test lunar effects in large samples.

Other large analyses

Haba-Rubio and colleagues (Sleep Medicine, 2015) studied 2,125 people with home sleep recordings and found no significant difference between lunar phases in subjective sleep quality or objective sleep duration.

Della Monica and colleagues (Journal of Sleep Research, 2015) retrospectively analysed 205 healthy adults. There was no significant overall effect, but in women total sleep time and some sleep stages were reduced close to the full moon, while REM increased in men. They called this limited evidence.

Can bright moonlight in the bedroom disturb sleep?

Bright light in the bedroom can disturb sleep, so a full moon shining through an uncovered window is a plausible and fixable explanation for a restless night. This is separate from the lab findings above, which came from rooms with no view of the moon.

What sleep guidance says about light

The Sleep Foundation states that light exposure at night can hinder transitions between sleep cycles and reduce sleep quality, and it suggests making the bedroom as dark as possible. It describes blackout curtains as blocking most outside light, and eye masks as an option if you cannot remove every light source.

The NHS similarly advises a dark, quiet bedroom, with curtains, blinds or an eye mask if needed.

None of these sources measured moonlight itself, so they cannot say how much is enough to wake someone. If your room is visibly bright on full moon nights, a blind or mask costs little and is easy to test.

Why does believing in the moon effect colour how nights are reported?

Belief in a moon effect can colour how nights are remembered and reported, because people notice and recall events that fit what they already expect. This is a general feature of memory and attention, so it is reasoning, not a finding from the studies above.

The recall problem

If you expect to sleep badly under a full moon, a poor night on that date stands out and is filed as proof, while a poor night at the new moon is forgotten as ordinary. Over months, memory can seem to confirm a pattern that a written record would not. The 2013 volunteers slept in a windowless lab, so expectation and moonlight were largely removed there, which is part of why the later null results matter.

How can you check your own full moon and sleep pattern?

You can check your own full moon and sleep pattern by recording the moon phase and a morning sleep rating every day for one lunar month, about 29 days, then comparing the full moon nights with the rest. A flat result is a useful answer too.

Caffeine can easily muddy a month of notes, so read whether caffeine really ruins your sleep before you begin.

The 29-day log

The table shows a made-up month with approximate moon phases. Copy the columns and fill in your own numbers.

A simple way to compare

In this made-up month, the full moon night scored 2 and 6.5 hours, which looks dramatic. Yet days 9, 12, 19 and 24 also scored 3 with no full moon nearby. One bad night is not a pattern, so compare the average of the nights around the full moon with your overall average.

When should poor sleep be checked by a clinician?

Poor sleep should be checked by a clinician if it lasts for months, does not improve after changing your sleep habits, or affects your daytime functioning. The NHS advises speaking to a GP if changing your sleeping habits has not helped insomnia.

If bad nights happen weekly regardless of the moon, other causes are more likely. Loud snoring, gasping at night or heavy daytime sleepiness are also worth raising with a doctor. People who are pregnant, take regular medication or have a medical or mental health condition should not rely on general articles, and should not change any treatment based on sleep tracking.

Frequently asked questions

Does the full moon really make you sleep less?

Not reliably. A small 2013 lab study found about 20 minutes less sleep around the full moon, but a 2014 analysis of 2,097 nights and a 2015 study of 2,125 people found no clear effect. The current evidence does not support a firm conclusion that the full moon shortens sleep.

Why can I not sleep when there is a full moon?

Bright moonlight through an uncovered window is one plausible reason, and expecting a bad night can make a poor one feel more memorable. Other causes are far more common. Try blackout curtains or an eye mask, as NHS guidance suggests.

Does the full moon affect melatonin?

One small 2013 study reported lower melatonin around the full moon, but later larger analyses of sleep did not confirm a lunar effect. The melatonin result comes from only 33 volunteers, so it should be seen as an unconfirmed finding and not as a settled fact.

Can a sleep tracker show whether the moon affects my sleep?

A tracker can show how your recorded sleep varied across a lunar month, but it cannot show that the moon caused any change. Compare full moon nights with other nights over several months, and remember that stress, caffeine, alcohol and bedroom light can all shift the numbers too.

Should I use blackout curtains on full moon nights?

They are a reasonable, low-cost step if your room is visibly bright. The Sleep Foundation describes blackout curtains as blocking most outside light, and the NHS suggests curtains, blinds or an eye mask if needed. Try it for a week.

Final thoughts

Here is the short recap.

• A small 2013 lab study found changes in sleep near the full moon, but larger later analyses mostly found no clear effect.
• A bright bedroom is a fixable factor, whatever the moon is doing.
• Written records over a lunar month beat memory for checking your own pattern.

Your turn: Do you notice your sleep changing around the full moon, and does a blind or mask make a difference? Tell us in the comments.

Sources and further reading

1. Cajochen C, Altanay-Ekici S, Munch M, Frey S, Knoblauch V, Wirz-Justice A. Evidence that the lunar cycle influences human sleep. Current Biology, 2013. Record opened via Europe PMC.
2. ScienceDaily. Bad night's sleep? Full moon may be to blame (press summary of the 2013 study). ScienceDaily, 2013.
3. Cordi M, Ackermann S, Bes FW, and colleagues. Lunar cycle effects on sleep and the file drawer problem. Current Biology, 2014. Record opened via Europe PMC.
4. Max Planck Society. Does the moon affect our sleep? (summary of the 2014 re-analysis). mpg.de.
5. Haba-Rubio J, Marques-Vidal P, Tobback N, and colleagues. Bad sleep? Don't blame the moon! A population-based study. Sleep Medicine, 2015. Record opened via Europe PMC.
6. Della Monica C, Atzori G, Dijk DJ. Effects of lunar phase on sleep in men and women in Surrey. Journal of Sleep Research, 2015. Record opened via Europe PMC.
7. Sleep Foundation. Light and Sleep. sleepfoundation.org, accessed 2026.
8. NHS. Insomnia. nhs.uk, accessed 2026.
9. NHS Every Mind Matters. How to fall asleep faster and sleep better. nhs.uk, accessed 2026.