With the evenings so dark and grim, you’d think it would be easier to hunker down and fall asleep in winter. But if you find yourself tossing and turning at night, it’s time to set an alarm and get up and out in the morning.
It might sound counter-productive when you’re tired, but soaking up morning sunlight – even on cloudy days – can help us sleep at night, according to new research from the University of Washington
The study found that falling asleep later is common in winter months. And it’s all to do with the amount of light we get during the day – and when we get it.
To asses how our sleep changes throughout the seasons, researchers fitted more than 500 undergraduates with wrist trackers to monitor their sleep patterns and light exposure.
Data indicated that students were getting roughly the same amount of sleep each night regardless of the season. However, they were falling asleep later in winter months compared to summer months (and getting up later too the next day).
In fact, the results found that on school days during the winter, students were going to bed on average 35 minutes later and waking up 27 minutes later than summer school days.
The researchers concluded that getting insufficient light during the day leads to problems at night.
“Our bodies have a natural circadian clock that tells us when to go to sleep at night,” said senior author Horacio de la Iglesia, a UW professor of biology.
“If you do not get enough exposure to light during the day when the sun is out, that ‘delays’ your clock and pushes back the onset of sleep at night.”
The data indicated that each hour of daytime light “moved up” the students’ circadian phases by 30 minutes. The researchers also found that daytime light exposure had a greater impact than evening light exposure, which is why it’s beneficial to get your vitamin D hit earlier in the day. And unfortunately, artificial light won’t cut it.
“Light during the day – especially in the morning – advances your clock, so you get tired earlier in the evening, but light exposure late in the day or early night will delay your clock, pushing back the time that you will feel tired,” said de la Iglesia.
“Ultimately, the time that you fall asleep is a result of the push and pull between these opposite effects of light exposure at different times of the day.”
So, what does all this mean?
Put simply, it means if you can find the motivation to get out of bed in the morning, resist that lie-in and get outdoors, you’ll sleep better that night.
“Many of us live in cities and towns with lots of artificial light and lifestyles that keep us indoors during the day,” said de la Iglesia.
“What this study shows is that we need to get out – even for a little while and especially in the morning – to get that natural light exposure. In the evening, minimise screen time and artificial lighting to help us fall asleep.”
