How did the moon look last night? Full? Crescent-shaped? Believe it or not, the moon phase may actually be relevant to you and your sleep.
A research team in Switzerland recently performed a retroactive study (i.e., using data that had been previously collected) to examine whether the lunar cycle affects sleep. Data from 17 individuals were obtained, and measures of interest were sleep latency (how long it takes to fall asleep), sleep quality and depth, total sleep time, and melatonin levels. Melatonin is a sleep-regulating chemical that keeps the body’s internal clock running on schedule. These data were compared with which lunar phase it happened to be that day. These phases were 0–4 days, 5–9 days, and 10–14 days to closest full moon.
Large differences were found in sleep parameters based on lunar phase. Closer to the time of the full moon, participants had lower self-rated sleep quality, shorter total sleep time, shallower sleep, longer sleep latency, and even lower melatonin levels than nights when they were farther from the full moon.
These findings are actually quite incredible. It was already known that we have very predictable 24-hour internal sleep/wake rhythms (which also correspond with melatonin levels), but this is the first study to show a sleep cycle that corresponds with the lunar cycle. The fuller the moon, the worse the sleep. This may actually come as a relief to some, as many individuals become stressed or frustrated during or after a bad night of sleep. This worry may exacerbate sleep loss, setting up the conditions for even worse sleep. For those with sleep apnea, every minute of sleep counts, so worry must be minimized. If you are ever feeling like your sleep is just ‘off,’ don’t panic – it may be something very far out of your control – like the moon!
Cajochen, C., Altanay-Ekici, S., Münch, M., Frey, S., Knoblauch, V., & Wirz-Justice, A. (2013). Evidence that the lunar cycle influences human sleep. Current Biology, 23(15), 1485-1488.