According to folklore, the full moon does more than just turn us into raving lunatics and werewolves — it also affects our sleep, and not in a good way. A new study is now showing this is true — and that the influence of the full moon is far worse than we thought.
Top photograph: Philipp Schmidli.
There are many anecdotal accounts of the lunar cycle and its effect on our sleep. It’s been said that it’s harder to get to sleep and remain asleep during a full moon, and that a kind of ‘full moon hangover’ can take hold the next day — one that’s characterized by feelings of sluggishness.
Photograph: Miloslav Druckmüller.
But aside from these informal observations, scientists haven’t been able to to connect lunar cycles to human sleep behavior. That is, until now.
Back in 2000, scientists from the University of Basel, the Swiss Federal Institute of Technology and the Switzerland Centre for Sleep Medicine, conducted a 3-year study to analyze human sleep patterns and how they were influenced by age and gender. Now, some thirteen years later, the data acquired in that study has been re-analyzed to see if a correlation could be made between sleep regulation and the lunar cycle.
For the initial study, the research team recruited 33 volunteers across two age groups. They gathered all sorts of excellent data, both subjective and objective measures, including brain wave activity as measured by EEGs (specifically EEG activity during non-rapid-eye movement (NREM) sleep, which is a deep state of sleep), levels of sleep hormones (namely melatonin and cortisol), the amount of time it took the participants to fall asleep, the amount of time spent in deep sleep, and reports of how rested they all felt the following day.
The participants all slept in a dark room with no sight of the moon. And importantly, there was no mention of the moon or the lunar cycle. Which makes sense. The original study had absolutely nothing to do with the moon, so the participants could not have been made aware of it. Nor the scientists running the tests, for that matter. Thus, it was a de facto double-blind study.
According to the re-analyzed data, the moon does indeed impact on the quality of our sleep — and its influence is hardly subtle.
On the three or four nights surrounding a full moon, it took the participants five minutes longer to fall asleep, and they slept for 20 fewer minutes. Their EEG activity, which measured NREM sleep, fell by 30%. Their melatonin levels were lower and they reported feeling less rested the following day.
“This is the first reliable evidence that a lunar rhythm can modulate sleep structure in humans when measured under the highly controlled conditions of a circadian laboratory study protocol without time cues,” note the authors in their study.
So what accounts for this? Well, it can’t be gravity. It’s far too weak to have any influence on the human body. And tidal cycles are distinct from lunar phases.
The researchers speculate we’ve evolved an astronomical cycle — a kind of lunar circadian rhythm. It’s an evolved relic from the past when the moon was responsible for synchronizing human (or proto-human) behavior.
As for the mechanism behind it, it could have something to do with the suprachiasmatic nuclei, a tiny region of the brain responsible for the production of melatonin. Perhaps the lunar cycle is influencing the regulation of neurotransmitters and other chemicals.
Read the entire study at Current Biology: “Evidence that the Lunar Cycle Influences Human Sleep.”