December 22, 2022 – Falling asleep and waking up late this time of year? You may need to reset the sleep/wake clock. Getting outside and getting more sun — especially in the morning — may help, new evidence suggests.
Yes, using lights and screens at night can interfere with your sleep, but that’s not all, says Dr. Horacio de la Iglesia, a professor of biology at the University of Washington in Seattle. In fact, daylight is much brighter, even on cloudy days, than indoor lighting. So they are not the same.
In a study of 507 college students at the University of Washington, shorter daylight hours delayed sleep in winter by about half an hour compared with other times of the year.
“It’s important for several reasons,” De La Iglesia said.
First, teens and young adults tend to go to bed late, “or what we call a late sleeper, which bodes well for physical and mental health. Also, if you go to bed late, it can mean that you have trouble getting out of bed and end up sleeping poorly.” Less, and you’ll also add to what we call “social jetlag.”
Social jetlag, the difference in sleep duration between weekends and weekdays, “is also a predictor of poor health,” de la Iglesia said.
“An easy fix”
Poor sleep has more than one price.Researchers Estimate Cost of Sleep Disorders in 2021 $95 billion per year Diagnosed and treated in the United States.
“There’s a lot of money being invested in trying to develop drugs that improve sleep, prolong sleep, increase the circadian clock,” de la Iglesia said. But a simple movement, like a brisk walk in the morning, can help reset your sleep clock, “and it makes you feel better. That’s what we love about it—it’s easy to fix,” he says. “Even if you can get out for a short time, that should help you get ahead … and help you deal with the winter blues.”
The study focused on college students, but the findings may apply to people of other age groups, de la Iglesia said. Young teens, for example, may also benefit from getting more daylight.
“Seniors here are struggling in the winter, trying to get out of bed, and I think that should definitely apply to all age groups.”
Students wear automated data loggers on their wrists to measure activity and exposure. The intensity of outdoor light is at least 50 lux. The researchers compared findings across all four seasons, including the university’s summer sessions.
this study Published online in November at journal of pineal research.
If a later summer sunset means a later bedtime seems to make more sense, you’re not alone.
“While we have good reason to expect sleep to vary seasonally, we don’t have any clear predictions about which direction it will change,” de la Iglesia said. “In fact, our predictions were completely wrong.”
Compared with summer school students, the students fell asleep 35 minutes later and woke up 27 minutes later.
The researchers did not find any significant differences in sleep duration across seasons. But students used an alarm clock to wake up about 10 percent more often in the fall and winter than in the spring and summer.
Possible Multiple Health Effects
“My take is that exposure to sunlight seems to be more effective than exposure to artificial light — and that’s consistent with what we know,” says Karin Johnson, MD, medical director of the Baystate Regional Sleep Medicine Program in Springfield, Massachusetts . Get involved in research.
“In addition to sleep deprivation, the misalignment of social schedules with the body’s own schedule can affect health even when the average sleep duration is the same,” she said. “This effect helps explain why making DST permanent in winter could be exponentially worse than it would be for us in summer.”
A later midsleep midpoint — defined as the midpoint in clock time between falling asleep and waking up — in the evening and more social jetlag “is strongly associated with a number of health problems,” Johnson said. Metabolic syndrome and obesity, cardiovascular problems, depression, anxiety, and poorer performance and thinking skills are examples.
Going forward, de la Iglesia and colleagues hope to expand the research to other sites.
They plan to work with collaborators in San Diego, which has a lower latitude and different daylight variations. This may help answer the question of what happens on other school campuses where seasonal changes are less intense.
“Maybe it’s a matter of northern latitude,” de la Iglesia said.