You don’t have to be a werewolf to feel restless when the full moon rises.
A new study in the journal Current Biology suggests that people tend to get lower quality sleep around the time of full moons, snoozing an average of 20 minutes less than they do during a new moon.
“If you ask people, at least in Switzerland, about 40% report feeling the moon during sleep, or they blame the full moon for bad sleep,” said lead study author Christian Cajochen of the Psychiatric Hospital of the University of Basel in Switzerland.
That’s why he and his colleagues decided to investigate.
The study included 33 healthy volunteers, between ages 20 and 74. Participants slept under strictly controlled conditions in a laboratory with no windows, so they had no way of seeing the moon. They stayed in the laboratory for 3½ days. Humidity and temperature were controlled.
The full moon was associated with a 20-minute reduction of total sleep time, the study authors found.
Researchers also found that it took about five minutes longer for participants to fall asleep around a full moon than around a new moon. Deep sleep was, on average, 30% decreased around the time of a full moon.
People sleeping in the lab nearer to the day of a full moon also had lower evening levels of melatonin, a hormone important to circadian rhythm that drives the body’s cycles of day and night and, therefore, wakefulness and sleep.