True or false: does the full moon keep us from sleeping?

 The full moon is a phenomenon that intrigues as much as it fascinates or sometimes worries. One of the most widespread beliefs is that it affects the quality of our sleep. What is it really ? We take stock with Dr. Justine Frija-Masson, pulmonologist specializing in sleep and member of the French Society for Sleep Research and Medicine (SFMRS).

The full moon has always been associated with mysterious beliefs . If the myth of werewolves has had its day, others persist... The full moon is said to favor the hyperactivity of children and also influence the growth of our hair, but above all it would influence the quality of our sleep , disrupting our nights and leaving hours of sleeplessness  in its wake. Is there any truth to this myth, or is it just an unfortunate coincidence of timing? We take stock with Dr. Justine Frija-Masson, pulmonologist specializing in sleep and member of the French Society for Sleep Research and Medicine (SFMRS).

When do we speak of a real full moon?

As a reminder, the Moon is a star that rotates on itself and orbits the Earth, like a satellite. Depending on its location, it is therefore more or less illuminated by the Sun. There are four lunar phases: the new moon, the waxing moon, the full moon and the waning moon.

The full moon appears in the sky at least once a month (usually every 29.5 days) and corresponds to the phase during which the illuminated side of the Moon is entirely visible from Earth . This happens when Earth is between the Sun and the Moon, so the Sun's light hits the exposed lunar surface directly. Concretely, the Moon appears in the sky as a very luminous and complete disk.

Note: the true full moon only lasts a few moments (and not a whole night!), since the moon continues its rotation around the Earth, which itself rotates around the Sun.

Sleep: why do we sometimes sleep poorly during full moon evenings?

Can your nights really be disrupted by the full moon? Know that we are far from the scientific consensus  ! Some studies indeed suggest a correlation between the full moon and sleep disorders, while others have failed to observe any significant association. “It has long been thought that difficulty falling asleep and sleep problems that occur on full moon nights are linked to cognitive biases . In other words, it was thought that simply anticipating the occurrence of sleep disorders associated with the full moon could be the cause of sleep disorders, explains Dr. Frija-Masson. However, recent studies indicate that we actually tend to sleep less well on full moon nights . However, this remains marginal and does not concern everyone,” she believes.

One of the most recent studies in this area was published in January 2021 in the journal Science Advances (source 1), by a team of American researchers. Researchers studied the sleep habits of 98 people living in three indigenous communities in northern Argentina and 464 students in the Seattle area. They divided them into three groups: rural people without access to light, rural people with moderate access to light, and urban students. During the full moon, they found that the three groups took longer to fall asleep  : on average 22 minutes longer for rural people and 9 minutes longer for students.  Sleep duration also decreases depending on the group: on average 25 minutes less for rural people without access to light, 19 minutes less for rural people with access to moderate light and 11 minutes less for students.

What is the origin of these disturbances, according to the research team? The light emitted by the full moon . “Moonlight likely stimulates nocturnal activity and inhibits sleep,” the team concludes. In other words, the light given off by the full moon could modify our sleeping environment, influence our circadian cycles and thus disrupt our biological clock, explains Dr. Frija-Masson. On the other hand, the research team insists that the full moon would have no effect on the time of waking up . And to specify:

It is mainly the moonlight present during the first hours of the night which is most likely to impact falling asleep. Moonlight that appears late at night, when most individuals are asleep, should have little influence on the occurrence and duration of sleep (source 1).

That said, sensitivity to light can vary between people and few people  sleep with windows open  and risk being exposed to the Moon's rays while they sleep. Without forgetting that many factors can influence falling asleep and the quality of sleep, such as stress , diet, physical exercise , overall health... It is therefore difficult to know if the full moon is solely responsible for sleep disorders. sleep !


What other effects can the full moon have on humans and their environment?

The full moon is known to influence many elements: it influences the rhythm of the tides, the growth of plants and also the occurrence of seismic events. In theory, it could also have many effects on our health, our mood and our environment:

  • In addition to its relative impact on the quality of our sleep, some people believe that the full moon can intensify our dreams.
  • It would also exacerbate our emotions and  promote susceptibility, agitation, even aggressiveness . Some children are particularly prone to unusual hyperactivity.
  • Another tough belief: the full moon promotes hair health . Getting your hair cut on full moon nights would promote healthy regrowth; our hair would thus be shinier and stronger.
  • In some cultures, the full moon is also associated with a greater possibility of giving birth  and  an increase in fertility.
  • Some people also report feeling less hungry on full moon nights . And others, on the contrary, would have a devouring appetite on those evenings.
  • Finally, other people complain of migraines or more severe chronic pain on full moon evenings . Some women even complain of more severe menstrual pain

In practice, as Dr. Frija-Masson points out, none of these beliefs are scientifically supported! “If you suffer from significant problems that seem to you to be correlated with the full moon, make an appointment with your doctor ,” she advises.

How to sleep well at night and limit insomnia (during the full moon or not)?

As our expert points out, whether or not you believe in the influence of the full moon on sleep, it is essential to adopt good sleeping habits  and create an environment conducive to rest . Full moon evening or not, here are some tips for sleeping well:

  • Try going to bed and waking up at the same time every day , even on weekends, to regulate your body clock.
  • Make sure your bedroom is dark, quiet, and cool . To limit the potential impact of the full moon, use blackout curtains that will block outside light. If necessary, use earplugs to limit extraneous noise (but avoid falling asleep to music ).
  • Limit the consumption of stimulants like caffeine and nicotine after 2 p.m. 
  • Avoid heavy and/or spicy meals before bed and try to eat two to three hours before going to bed.
  • Focus on relaxing activities before bed , such as reading, meditation or yoga. If necessary, practice stress management techniques, such as deep breathing or visualization.
  • Establish a digital curfew and avoid phone, tablet or computer screens at least an hour before bed (blue light can disrupt melatonin production, says Dr. Frija-Masson).
  • Expose yourself to natural light and  exercise during the day (avoid exercising in the evening).
  • Once in bed, avoid looking at your phone and overthinking or worrying.  If you really can't sleep, get up and do something relaxing until you feel sleepy.
  • Finally, make sure your mattress and pillow provide adequate support to avoid discomfort that could disrupt your sleep.