Do you ever attribute your child’s wild or wound-up behavior to the presence of a full moon? If so, you’re far from the only parent to feel as though your child might open his mouth and howl at the dark sky. Our connection to the moon and to lunar cycles has been the subject of legend, speculation, and mythology for much of human history as we know it.

The relationship of human behavior — and sleep — to the shifting phases of the moon has also been the subject of scientific inquiry. While still scientifically underexplored relative to the influence of solar, seasonal, and circadian rhythms and clocks, the effects of lunar rhythms are being investigated by scientists across disciplines. There is mounting evidence that the lunar cycle influences physiological function and behavior in animals, including birds, fish, and other marine life.

With regard to its effect on human physiology, behavior, and sleep, the scientific findings of the impact of lunar rhythms has been mixed, with some findings pointing to associations between phases of the moon and changes to sleep patterns and activity levels, while other studies failing to show a link.

Full moon, less sleep

A new, large-scale international study examines the effects of lunar phases on the sleep and waking activity levels of children. Researchers from around the globe collaborated on this investigation, which included more than 5,000 children from 12 different countries. They discovered a change in children’s sleep patterns associated with the changing phases of the moon.

Researchers used data from the International Study of Childhood Obesity, Lifestyle and the Environment (ISCOLE), an ongoing research project with study sites in Australia, Brazil, Canada, China, Columbia, Finland, India, Kenya, Portugal, South Africa, United Kingdom, and the United States. The countries that participate in ISCOLE reflect a diversity of geographic location as well as a range of economic development and other sociocultural factors. (These participating nations represent five major geographic regions of the world: Europe, Africa, the Americas, Southeast Asia, and the Western Pacific.)

The children in the study were between the ages 9–11. A total of 5,812 children participated in the study, spread roughly evenly among the 12 participating nations. Sleep and waking activity levels were measured using waist-worn accelerometers. Researchers collected data on nighttime sleep duration, and sleep efficiency — the amount of time spent sleeping compared to the total amount of time spent in bed. They also assessed waking activity levels from light to moderate and vigorous, and overall sedentary time. The data collected was analyzed in relation to three different lunar phases:

  • Full moon (plus or minus 4 days)
  • Half moon (plus or minus 5–9 days from the nearest full moon)
  • New moon (plus or minus 10–14 days from the nearest full moon)

The scientists’ analysis revealed a small, but statistically significant, change to children’s sleep duration in connection with the full moon. The children slept an average of 4.9 minutes less during the time of the full moon, compared to the time of a new moon, for an average 1 percent reduction in total sleep time.

This was the only sleep and activity measurement that was associated with changing moon phases. Researchers found no links between the different lunar phases and children’s waking activity levels, sedentary time, or sleep efficiency.

Other evidence of the moon-sleep connection

While scientists didn’t find broad or dramatic shifts in children’s sleep patterns linked to the moon, their study — the first to examine the lunar influence of sleep in children across five major regions of the world — did establish a modest but meaningful link between sleep duration and lunar phases. This research aligns with other, previous studies that have demonstrated an association between human sleep patterns and the lunar cycle.

Swiss researchers in 2013 shared results of an in-laboratory study of sleep and lunar cycles. They found several significant changes to sleep patterns associated with the full moon:

  • Decreased sleep duration: participants slept 20 minutes less, on average, during the full moon phase
  • Delayed sleep: participants took an average of 5 minutes longer to fall asleep at or around the full moon
  • Reduced melatonin: participants showed lower levels of the “sleep hormone” at the full moon
  • Diminished sleep quality: Participants reported sleeping less soundly during the full moon phase
  • Changes to sleep architecture: Participants spent less time in slow wave sleep, and took longer to reach REM sleep, near to the full moon

This study garnered a lot of attention, as it strongly suggested links between human physiology and sleep and the phases of the moon. Additional studies subsequently reported similar changes to sleep patterns linked to the lunar cycle. One investigation — also conducted by scientists in Sweden — found reduction in sleep time of an average of 25 minutes near the full moon. Researchers also found changes to sleep architecture, particularly a change in the time it took participants to enter REM sleep around the time of a new moon. Participants, who slept in laboratory during the study, also demonstrated greater reactivity to environmental stimuli while asleep, during periods of a full moon.

A team of scientists from Europe, Canada, and the U.S. also found links between the lunar cycle and sleep duration, sleep efficiency and quality, and changes to slow-wave sleep and REM sleep.

Moon-sleep findings mixed

But not all evidence points clearly to an association between sleep and the lunar cycle, or demonstrates uniformly what that association may be. A recent study of more than 2,000 men and women in Switzerland found no link between the phases of the moon and sleep duration or sleep quality.

Another recent investigation — one of the few other studies to look specifically at children’s sleep in relation to lunar phases — found changes to sleep and activity levels that were distinctly different from the current study. In this study, Danish researchers studying 795 children ages 8–11 found that children slept slightly more — an average of 3 minutes — around the time of the full moon, not less. In addition, they found that children’s activity levels also changed in relation to the moon, and that children were slightly less active during the full moon phase, by an average of about 4 minutes of moderate or vigorous activity.

The folkloric link between sleep and waking behavior and the moon has been with us for a very long time. We’re only at the beginning of a scientific exploration of this possible connection, and how it may affect our sleep patterns — and our children’s. We know that other forms of animal life possess physiological and behavioral connections to the moon. More research — sure to come — may eventually show us whether we do as well.

Sweet Dreams,

Michael J. Breus, PhD

The Sleep Doctor™

Originally published at on May 20, 2016.

Originally published at