Photo

The lunar cycle has been tied to a range of mysterious powers, from increases in violent crimes and hospital admissions to fertility and blood loss, and scientists consider most such beliefs nonsensical.

But now Swiss researchers have found evidence that the lunar cycle may affect sleep patterns. They found the connection by testing 33 healthy men and women, ages 20 to 74, in a sleep laboratory, and correlating the data with the moon’s phases. The study appears in the Aug. 5 issue of Current Biology.

Melatonin levels, total sleep time and delta sleep time (the deepest sleep, as recorded by EEG) reached their lowest levels at full moon, and their highest as the moon waxed and waned. The average time it took to fall asleep and the time to arrive at REM sleep (the type of sleep in which dreams occur) followed the opposite pattern, longest at the full moon and shorter as it waxed and waned.

Christian Cajochen, a professor of neuroscience at the University of Basel who led the study, was surprised and puzzled by the finding.

“The only explanation we could come up with is that maybe there is a lunar clock in the brain, as found in other species like fish and other marine animals,” he said. “But we don’t have direct evidence for that.”