Sleeping With Dim Light Could Lead to Serious Health Risks, Reveals New Study

Even in a state of sleep, you could still be at risk of health problems, even the young ones. To protect your health, close the blinds entirely and turn of all lights before bed, Northwestern physicians suggest so.

New study found that sleeping with even a small amount of light may be harmful for your health, CNN reported. Even with the dim light on may raise the blood sugar and heart rate of healthy young people.

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Details of a sleep lab experiment presented in Northwestern Now show that even moderate light exposure during sleep harms heart health and increases insulin resistance.

Results of the study demonstrates that this setup "impairs glucose and cardiovascular regulation, which are risk factors for heart disease, diabetes and metabolic syndrome," said senior study author Dr. Phyllis Zee, chief of sleep medicine at Northwestern University Feinberg School of Medicine and a Northwestern Medicine physician.

"It's important for people to avoid or minimize the amount of light exposure during sleep," she advised.

Lights on or lights off?

If you were used to sleeping with the lights on, here's why you should consider switching it off:

As our brain repairs and our bodies rejuvenate at night while we sleep, our heart rate typically drops and slows down, as it should. A previous study published in AHA Journals show that an increased heart rate during this period leads to future heart diseases and early death.

According to the new study, light increases heart rate, even dim lights from your TV set. Light exposure at daytime activates sympathetic nervous system, and consequently increases heart rate. This kickstarts our alertness to "meet the challenges of the day."

The study indicates that exposure to light at nighttime has similar effect, even in a moderately-lit room.

"Even though you are asleep, your autonomic nervous system is activated," said Dr. Daniela Grimaldi, a co-first author and research assistant professor of neurology at Northwestern. "That's bad. Usually, your heart rate together with other cardiovascular parameters are lower at night and higher during the day."

Moreover, exposure to light during sleep spikes insulin resistance, causing blood pressure to go up, and makes people overweight and obese.

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How To Get Better Sleep

Based on the study, Zee advised to "clearly pay attention to the light in your bedroom."

"Make sure that you start dimming your lights at least an hour or two before you go to bed to prepare your environment for sleep," she said. This is something that may vary depending on the source of lighting in your room.

If you prefer a dim light, keep it at floor level "so that it's more reflected rather than right next to your eye or bed level," Zee suggested.

"These findings are important particularly for those living in modern societies where exposure to indoor and outdoor nighttime light is increasingly widespread," Zee said.

"If you're able to see things really well, it's probably too light."