It is possible to predict bedtime from ``amount of light exposure'', and the reason why bedtime is later in winter than in summer is also found

Human sleep habits are influenced by various factors, and it is known that exposure to 'light' especially affects sleep. A new study that tracked the sleep patterns of more than 500 college students from 2015 to 2018 found that human sleep patterns fluctuate depending on the season, ``the more light you get during the day, the faster you go to bed''. became.

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A research team at the University of Washington, USA, asked 507 undergraduate students to wear a wrist monitor and conducted a study to track sleep patterns from 2015 to 2018. Seattle, where the University of Washington is located, is a city at high latitudes. During the summer solstice, which has the longest day of the year, the sun shines for nearly 16 hours from 5:00 to 21:00. It is characterized by the fact that the sun only comes out for about 8 hours around this time.

Professor Horacio de la Iglesia , co-author of the paper, said, 'We expected students to stay up late in the summer due to the amount of light available.'

When we actually analyzed the data, we found that the students slept pretty much the same every night, regardless of the season. However, contrary to the expectation that 'summer will be later', bedtime turned out to be 35 minutes later on average in winter, and wake-up time was 27 minutes later in winter. Surprisingly, people tended to go to bed later during periods of less sunlight.

It was also shown that the circadian rhythms of the university students who participated in the study were delayed by up to 40 minutes in the winter compared to the summer. I thought I was pushing back.

The research team points out that the reason why the circadian rhythm is delayed is the difference in sunlight hours between summer and winter. When the data was analyzed, it was found that an hour of light exposure in the daytime accelerates the circadian rhythm by about 30 minutes, and an hour of light from lights or computers after dusk slows the circadian rhythm by about 15 minutes. It turns out. In addition, although it is often cloudy in Seattle in winter, it is said that this effect existed even in winter because it is brighter than indoors even if it is cloudy.

Professor de la Iglesia says, ``Light exposure during the day, especially in the morning, advances your body clock and makes you sleepy in the evening. Ultimately, the time to fall asleep is a product of this conflicting effect of exposure to light at different times of the day.'

The results of this study suggest that seasonal changes in daylight hours affect circadian rhythms, even under conditions where nighttime light is commonplace in modern society. Professor de la Iglesia said, ``Many people live in cities and towns with a lot of artificial light and lead indoor lifestyles during the day. 'It means going outside and getting some natural light, and reducing screen time and lights at night can help you fall asleep.'

in Science, Posted by log1h_ik