31 January 2021
You may have noticed brighter night skies recently as we experienced a full moon. NASA reports the event, called the Wolf Moon, began Thursday afternoon and ended Saturday morning. But did you notice any changes in your personal sleep patterns in the days leading up to the full moon?
As the latest full moon was beginning, a new study was released suggesting that a full moon can affect human sleep cycles. Researchers confirmed that the nights leading up to a full moon have more natural light available after the sun goes down.
The new research found that in the days before a full moon, people go to sleep later in the evening and sleep for shorter periods of time.
The results were reported in a study appearing in the publication Science Advances. The research was led by biology professor Horacio de la Iglesia of the University of Washington.
"When we looked at the data it was right there - we didn't expect that pattern at all," de la Iglesia said in a video about the findings. He said the study provided clear evidence that a person's sleep-wake cycle is "synchronized" with changes the moon goes through.
The moon takes 27.3 days to orbit Earth, but it takes 29.5 days to complete a full cycle from New Moon to New Moon. The new study measured the sleep patterns of test subjects as the moon progressed through at least one whole 29.5-day cycle. Some subjects were tested through two moon cycles.
On average, people involved in the study slept about 52 minutes less on nights before a full moon. They also went to bed about 30 minutes later. The research showed that people had the latest bedtimes and the shortest amount of sleep during the nights that were three to five days before a full moon.
"I became one of the subjects of the study and when I looked back on my own data I could not believe how much my sleep changed," de la Iglesia said.
Effect on sleep in different areas
Past studies by de la Iglesia's team and other research groups have shown that access to electricity has a clear effect on sleep. So the team included this element in their research.
The study involved 98 individuals living in three different communities of Toba indigenous people in Argentina. Each community had different access to electricity. One rural community had no electricity access, while a second had only limited access. A third community was in a more populated area and had full access to electricity.
Sleep data was collected electronically from the individuals through wrist monitors. The research team said it believes this method resulted in more effective data than some past studies that depended only on user-reported sleep data.
In addition to the indigenous communities, the researchers also examined sleep data on 464 college students in the Seattle, Washington area. That data had been collected for a separate study. The researchers said they discovered the same moon cycle patterns in the sleep data from the students.
"Although the effect is more robust in communities without access to electricity, the effect is present in communities with electricity," de la Iglesia said.
The scientists say further research is needed to help explain other possible causes for the changes in sleep patterns in the test subjects. Such causes could involve biological differences in individuals or social patterns within communities.
I'm Bryan Lynn.
Bryan Lynn wrote this story for VOA Learning English, based on reports from the University of Washington, Science Advances and NASA. Hai Do was the editor.
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Words in This Story
pattern – n. a particular way that something is often done or repeated
cycle – n. a series of events that happen in a particular order and are often repeated
synchronize – v. make something happen at the same time as something else
access – n. the ability to use or take part in something
indigenous – adj. produced in or existing naturally in an area
monitor – n. a device used to measure something, such as heart rate
robust – adj. strong and healthy