A full moon

A full moon (Tiziana Fabi/Getty-AFP Photo)

Tossing and turning under a full moon? Turns out you’re no lunatic, just subject to lunar cycles.

In folk tales, and around dinner tables — not to mention on Halloween — people have long talked about the effects of the moon on human behavior. But science hasn’t backed up belief. Now scientists at the University of Basel in Switzerland say there’s evidence that people sleep worse around the time of a full moon.

Their work was published Thursday in the journal Current Biology.

Scientists, led by Christian Cajochen, analyzed the sleep of 17 volunteers ages 20 to 31 and 16 volunteers ages 57 to 74 in a laboratory, looking at brain patterns, eye movements and hormone secretions. They set up conditions so that light and time cues, and the potential for biased beliefs about the moon and sleep were not factors. The participants did not know the researchers were looking at the effect of lunar cycles on sleep.

The moon’s effects on tides and on various marine species have been documented, but the researchers say this is the first time it has been shown that “a lunar rhythm can modulate sleep structure in humans.”

What they found was that in the four days around the full moon people took five minutes longer to fall asleep and they slept 20 minutes less. The participants said they felt as though their sleep had been poorer, and they had lower levels of the hormone that regulates sleep, melatonin.

“Lunar rhythms are not as evident as circadian rhythms and are thus not easy to document,” the scientists wrote. “But they exist. Their role is mysterious.”

Just ask the poets. And the dreamers.

Mary.MacVean@latimes.com

@mmacvean on Twitter