The journal Current Biology recently published a study showing that human sleep appears to be affected by the phases of the moon (italics and bold mine):
The lunar cycle modulates human sleep and melatonin rhythms
“Endogenous rhythms of circa-lunar periodicity (∼29.5 days) and their underlying molecular and genetic basis have been demonstrated in a number of marine species [1,2]. In contrast, there is a great deal of folklore but no consistent association of moon cycles with human physiology and behavior . Here we show that subjective and objective measures of sleep vary according to lunar phase and thus may reflect circalunar rhythmicity in humans. To exclude confounders such as increased light at night or the potential bias in perception regarding a lunar influence on sleep, we retrospectively analyzed sleep structure, electroencephalographic activity during non-rapid-eye-movement (NREM) sleep, and secretion of the hormones melatonin and cortisol found under stringently controlled laboratory conditions in a cross-sectional setting. At no point during and after the study were volunteers or investigators aware of the a posteriori analysis relative to lunar phase. We found that around full moon, electroencephalogram (EEG) delta activity during NREM sleep, an indicator of deep sleep, decreased by 30%, time to fall asleep increased by 5 min, and EEG-assessed total sleep duration was reduced by 20 min. These changes were associated with a decrease in subjective sleep quality and diminished endogenous melatonin levels. 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.”
Commenting on the study, Scientific American noted:
- “Earlier work with marine creatures has found that the cycle of the moon is linked to some behaviors in those species and is an essential driving force behind reproductive timing for certain worms…”
- “The researchers found that brain activity related to deep sleep dropped by 30 percent and the study participants also showed reductions in their levels of melatonin, a light-sensitive hormone that helps control the natural sleep–wake cycle.”
- “On average, their sleep quality was about 20 percent worse during the full moon as compared with the new moon.”
It appears from this study that at the time of the Full Moon total sleep duration is reduced by 20 minutes. I wondered if this effect was somehow related to the traditional orb of the Moon in astrology, so I did a quick calculation based on the hypothesis that the average duration of sleep is about 8 hours per night.
Doing the math, 20 min divided by 8 hours (480 min) = 0.0417, or about 4.17% of the night’s sleep.
4.17% of a circle (360 degrees) is 15 degrees, which is very close to the traditional orb of the moon’s influence.
William Lilly allotted the Moon an orb of 12 – 12.5 degrees, and the sun an orb of 15 – 17.5 degrees. The Full Moon (and all the moon’s phases) involve the sun and the moon, and the 15 degrees calculated above lies between the traditional orbs of the two luminaries.
To me this is a rather remarkable coincidence.