Sleeping with Light Is Unhealthy

While the longest day of the year has passed. There is still more light later in the evening than most of us expect. Some of us who aren’t great at time keeping can easily find our schedules thrown off this time of year and end up eating dinner late just because the daylight cues confuse us!

The long daylight hours are lovely. But there’s one place you don’t want more light: your bedroom. Very few of us sleep in a completely dark room. Whether it’s a hall light, streetlight or TV, most of us have some form of light in our bedrooms. But, new research suggests that even dim lighting during sleep is unhealthy.

Research from Northwestern Univ. found that light exposure during sleep is linked to a higher risk of blood sugar concerns, obesity and high blood pressure in older people. Older research from the same group found that dim light exposure at night raised the blood sugar and heart rate of younger adults. They wanted to see if the pattern was the same for people as they aged. The new results show that there could be a cumulative effect over years of nighttime light exposure.

The study used 552 people between the ages of 63 and 84. They wore smart wristbands that tracked them for seven days so that the researchers could get real-world results instead of having people come into a sleep lab. Less than half of them slept in a fully dark room.

We were frankly surprised to find out that more than half of the older adults were sleeping with some light at night,” Dr. Minjee Kim said. “Adults who slept with some light during their sleep period were generally exposed to dim light.”

The people who slept with light were 74 percent more likely to have hypertension, 82 percent more likely to be obese and 100 percent more likely to have blood sugar concerns. The researchers believed there could be several reasons for their results. Light regulates the body’s circadian rhythm that controls so much of physical health. Sleeping with light may lower melatonin that aids circulatory and metabolic health. And, light may trigger the autonomic nervous system’s fight or flight reaction in a person’s sleep, so they aren’t getting rest and aren’t slowing their breath and heart rate as much as they should.

There’s hope for turning it around, though. Just cutting out the light might make a big difference. “It may be as simple as not using electronic devices near the sleeping place and blocking light with a sleeping mask,” said Dr. Kim. “If people need to use a night light for safety, they should try to keep it as close to the ground as possible to minimize light entry to the eyes. If they need to use the bathroom at night, and it is dangerous to walk in complete darkness, try to use dim light for the shortest necessary period.”

Banner image: Jp Valery via Unsplash

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