Exposure to natural light during the day may help you sleep better

Exposure to natural light during the day may help you sleep better

ISLAMABAD, (Online) - During the winter months when the days are shorter and darker, many people spend less time outdoors and don’t get as much natural light. This can affect everything from mood and energy to sleep.

Prior studiesTrusted Source indicate that at least 30 minutes of exposure to natural sunlight has a significant impact on the body’s internal clock, promoting more restful sleep.

Now, a recent study revealed some interesting insights about our bodies’ sleep patterns and demonstrates the value of getting outside during the day, even when it’s overcast.

The findings, recently published in the Journal of Pineal ResearchTrusted Source, show that not getting enough natural light during the day causes problems when it comes to getting quality sleep at night.

“Exposure to daylight is really critical to maintain a healthy circadian system and the sleep hygiene that comes with it,” senior study author Horacio de la Iglesia, PhD, a biology professor at the University of Washington, told Healthline.

How sleep patterns shift with the seasons

For the study, 500 student participants at the University of Washington in Seattle wore wrist monitors that allowed researchers to monitor their sleep patterns throughout the four seasons.

The data show that students were getting about the same total amount of sleep each night despite whether it was winter or summer.

Yet during the winter months, students who fell asleep later at night woke up later in the morning, a time of day in the region when there is less daylight and it’s cloudy outside. On average, they went to sleep 35 minutes later and woke up 27 minutes later on winter school days compared to summer school days.

Because there is less daylight in the winter, the students’ sleep-wake pattern came as a surprise to the researchers. For context, Seattle gets about 16 hours of sunlight on the summer solstice and just over 8 hours of sunlight on the winter solstice.

According to researchers, students stayed up late and slept in because they didn’t get enough exposure to natural light during the winter months.

Getting natural light during the daytime advances the body’s biological clock that times your sleep, de la Iglesia explained. He said this helps make it easier to fall asleep at a reasonable time and wake up in the early morning.

Of course, it’s important to note that a possible limitation of this study is its location, as Seattle is notoriously cloudy. Further studies in different geographical regions are needed to confirm whether natural light exposure can effectively promote sleep.

“We would love to determine how much the delay during the winter months depends on latitude,” de la Iglesia said.

“We are hoping to collaborate with other undergraduate campuses to determine if in more southern latitudes the seasonal differences and specifically the delayed winter timing of sleep go away.”

How daylight affects circadian rhythms

Both daytime and evening light affects the timing of your circadian cycles.

While exposure to daytime light helps promote restful sleep at night, evening light may delay your internal clock and interfere with your ability to fall asleep and get good quality sleep.

“Normally, light is a signal for wakefulness — and light in the evening hours can suppress melatonin and impair sleep,” Dr. Alex Dimitriu, double board-certified psychiatrist and sleep medicine specialist and founder of Menlo Park Psychiatry & Sleep Medicine and BrainfoodMD, told Healthline.

According to the University of Washington study, each additional hour of daytime light was linked to improved circadian rhythms. The authors also noted that bright midday light was more effective for improving sleep than morning light.

“In this study, most interestingly, besides times of sunrise and sunset, the authors noted that midday light of bright intensity plays a very powerful role and correlates with delay in circadian patterns,” Dr. Dimitriu stated.

“The [researchers] also suggest that daily exposure to daylight is key to prevent this delayed phase of the circadian clock and thus circadian disruption that is typically exacerbated in high-latitude winters.”