People have complained about a poor night's sleep during a full moon. Now, a new study has found evidence that Earth's closest galactic neighbor appears to impact the quality of sleep in humans.
, a sleep researcher at the Psychiatric Hospital of the University of Basel in Switzerland, led a study analyzing sleep study data measurements, including brain activity, of 33 individuals who had previously been assessed in a sleep clinic.
To their surprise, Cajochen said researchers found the subjects slept more poorly when the moon was full.
“Around [a] full moon, people had less deep sleep, about 30 percent less deep sleep. They slept in general 20 minutes shorter, and it took them five minutes longer to fall asleep,” he said.
Cajochen said little is known about the impact of moon phases on humans, whose sleep is influenced by a 24-hour internal clock called a circadian rhythm, a biological process driven by hormone fluctuations that control the sleep-wake cycle and feeding patterns.
This internal clock also is affected by periods of light and dark, according to Cajochen, who said researchers found that levels of the hormone melatonin, which readies the body for sleep, also were lower in subjects during a full moon.
“There is darkness outside and our body has to adapt to darkness behavior, which means in humans, sleep. So it’s a sleep-preparatory hormone. And this was reduced during full moon phase, although they didn’t see the light. And this probably causes or caused this little sleep disturbance,” he said.
Cajochen speculates the sleep disturbance, which is due to what he calls a “circalunar” rhythm, might be a holdover from prehistoric times, influencing human reproduction and other activities as it now does in animals including sea creatures.
“There is evidence these two clocks talk to each other - the circadian and the circalunar clock in other species. But we don’t have any clue in humans, first of all, whether there is a clock, a circalunar clock, and if yes, where is the clock, you know where in the brain. We know it about the circadian clock, we know exactly about the location, where it is for the circadian clock, but the circalunar clock is still mysterious,” he said.
Cajochen said a lunar clock, if it exists, also may influence cognitive performance in humans and our moods.
An article on the influence of the moon on human sleep is published in the journal Current Biology