I recall reading an article, many years ago, in the New Scientist concerning a study into the effect of the lunar cycle on men. It was suggested that some men showed a physical response, such as a change in the rate of beard growth.

I don't know if it was part of the NS article, but this has obvious links with werewolf stories.

I have a kind of wish for this to be true. It seems feasible that some response to the moon should exist in men as well as women, given our evolution in the presence of that near neighbour.

Edit, further information:

While the orbital period of the Moon is 27.322 days, Wolfram Research state that the mean time for one lunar phase cycle (i.e., the synodic period of the Moon) is 29.530589 days.

An article on the Biology Online website cites research into lunar influence on animals and plants. This does not specifically mention the influence on men but, more generally, animals.

  • Please improve this question by adding references.
    – Sklivvz
    Commented Mar 12, 2011 at 12:19
  • 11
    I think it confuses the question to bring up the moon. It's still valid to ask if men, like women, have biological cycles of about that length. It's certainly possible. I'd be interested to know. Commented Mar 12, 2011 at 18:06
  • @Mike. Good point. Perhaps I should have left the question more open-ended, but my own (unscientific) view is that it is likely the Moon affects Life on Earth beyond the sea tides. With this in mind, and in response to other answers here, I've added references to Moon period data and research into effects on animals. If this confuses things further, I guess the question may be closed :(
    – Zzzzzzz123
    Commented Mar 13, 2011 at 10:59
  • "Men’s testosterone appears to cycle throughout the day, month, and possibly even the seasons, affecting their moods and sexual desire. ... But what about men? Do they have hormonal cycles too? Some hormones researchers say no; men don’t cycle. Others say yes, but their cycles are less studied and less dramatic than women’s. Men’s testosterone cycles fluctuate from higher in the morning to lower each evening, and, according to some ... studies, the hormone level fluctuates seasonally as well, peaking in October and ebbing in April" apa.org/monitor/2011/03/hormones.aspx
    – A E
    Commented Mar 2, 2015 at 23:34

2 Answers 2


The lunar cycle has no effect on human behavior in any way. No scientific study ever conducted has shown any correlation between the moon cycles and any human activity.

See Wikipedia's article on the Lunar Effect for a good summary of studies conducted:

Psychologist Ivan Kelly of the University of Saskatchewan (with James Rotton and Roger Culver) did a meta-analysis of thirty-seven studies that examined relationships between the moon's four phases and human behavior in 1996. The meta-analysis revealed no significant correlation. They also checked twenty-three studies that had claimed to show correlation, and nearly half of these contained at least one statistical error. 1

1: Kelly, Ivan; Rotton, James; Culver, Roger (1986), "The Moon Was Full and Nothing Happened: A Review of Studies on the Moon and Human Behavior", Skeptical Inquirer 10 (2): 129–43. Reprinted in The Hundredth Monkey - and other paradigms of the paranormal, edited by Kendrick Frazier, Prometheus Books. Revised and updated in The Outer Edge: Classic Investigations of the Paranormal, edited by Joe Nickell, Barry Karr, and Tom Genoni, 1996, CSICOP.

  • 6
    How is this relevant? He is talking about beard growth and you're talking about human behavior.
    – Borror0
    Commented Mar 12, 2011 at 4:01
  • @Borror0 He asked about physical response. Beard growth was just one example. And even with beard growth, the force of gravity exerted by your bed pillow is stronger than the moon's gravity, so the one possible influence the moon could have is pretty irrelevant. Commented Mar 12, 2011 at 5:09
  • Please improve this answer by using better citations than wikipedia
    – Sklivvz
    Commented Mar 12, 2011 at 12:20
  • 4
    @SKlivvz: Double standards? Here is a posting with 3 citations of wikipedia: skeptics.stackexchange.com/questions/421/… plus Photoshop Disasters. Other sources may as well be unavailable in the future - wikipedia is at least easily available now. Commented Mar 13, 2011 at 2:59
  • 1
    This doesn't really answer the question.
    – user11643
    Commented Sep 26, 2017 at 13:49

While women do have something like a monthly cycle it's not linked to the moon. The mean cycle length is 29.1 days while the moon cycle is 27.3 days.

Even if there would be a monthly cycle among men it's therefore unlikely that it would sync with the moon. It would make much more sense if a possible monthly cycle would sync with the cycle of a nearby female.

  • 4
    I've added some reference links to my original question, including one to a source stating that the average period of the moon is 29.5 days. There's also an article on the moon's effects on animal and plant life.
    – Zzzzzzz123
    Commented Mar 13, 2011 at 10:26
  • 1
    @Zzzzzzz123: The moon cirles around the earth, and together with the earth around the sun. So while the orbit is 27.3 days, the angle towards the sun is about 360°/12 off after one month which explains while a mooncyle is about 2 days longer. See the picture below. Commented Jun 16, 2015 at 1:08
  • 1
    The question is whether men have a monthly cycle like women. You don't answer that.
    – user11643
    Commented Sep 26, 2017 at 13:51
  • 2
    @user unknown: you seem to be suggesting that the amount of light that the moon reflects would somehow be less important than some abstract notion of its "orbit". Commented Sep 29, 2017 at 1:36

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