Scientists say they've found evidence that human sleep patterns are timed to the phases of the moon, and that people sleep 20 minutes less on average during a full moon.

"The lunar cycle seems to influence human sleep, even when one does not 'see' the moon and is not aware of the actual moon phase," study co-author Christian Cajochen, a chronobiologist at the University of Basel in Switzerland, said in a statement.

Cajochen says his team's findings, detailed in the July 25 issue of the journal Current Biology, could be evidence of a biological "circalunar clock" ticking inside of humans.

Similar to the circadian clock that helps humans and other animals sync their physical and behavioral changes to a 24-hour day-night