The folklore has saddled the moon with great responsibilities: moods, crime, and even psychosis are blamed on the earth’s only constant natural satellite. But can the “moon effect” interfere with sleep?
Scientists have long understood that human activities are facilitated by light, whether sunlight, moonlight, or artificial light. But a study suggests that our sleep ability is clearly affected by the lunar cycle, even when artificial light sources are taken into account.
Using pulse monitors, researchers detected sleep patterns in 98 individuals living in three indigenous communities in Argentina for one to two months. One rural community had no access to electricity, a second rural community had limited access to electricity, while a third community was located in an urban area and had full access to electricity.
Participants in all three communities showed the same pattern of sleep changes as the moon progressed during its 29.5-day cycle, while the sleep duration changed by between 20 and more than 90 minutes, and the sleep time from 30 to 80 minutes.
In each community, the peak of participants slept less and stayed up later in the three to five day period leading up to full moon nights, and the opposite occurred in the nights preceding the new moon, the authors found.
The data were somewhat surprising, as the initial expectation was of less sleep and more activity during the full moon nights, said Horacio de la Iglesia, a professor of biology at the University of Washington. “But it seems that the nights before the full moon have the most moonlight during the first half of the night.”
It is not surprising that data show that the “lunar phase effect” on sleep appears to be stronger the more restricted access to electricity was.
In an effort to confirm their findings, the researchers compared their results with similar data from 464 students in Seattle studying at the University of Washington. They found the same oscillations in sleep patterns.
“Together, these results strongly suggest that human sleep is synchronized with lunar phases, regardless of ethnic and socio-cultural background and level of urbanization,” the researchers wrote in the journal Science Advances.
De la Iglesia added: “Our people tend to believe that we have succeeded in controlling nature, and the use of artificial light is an excellent example of this. But it turns out that there are some forces of nature that we can not get away from. ‘
Derk-Jan Dijk, a professor of sleep and physiology and director of a sleep research center at the University of Surrey, noted that the researchers did not address internal influences such as circadian clocks that can affect sleep patterns.
Previous research on the effect of the moon on sleep was contradictory: studies examined sleep in the laboratory (where external light is protected) and most were not designed to look specifically at the impact of the moon, said dr. Ciro della Monica said. a research fellow at the Surrey Sleep Research Center.
“The study is very interesting, but as the authors themselves state, they cannot determine causality,” Della Monica said. “However, the data is strong and new.”