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Science

Sleeping With the Light On May Be Harmful To You (northwestern.edu) 36

"Exposure to even moderate ambient lighting during nighttime sleep, compared to sleeping in a dimly lit room, harms your cardiovascular function during sleep and increases your insulin resistance the following morning," announced Northwestern Medicine, citing a new study recently published in the Proceedings of the National Academy of Sciences.

The Washington Post reports: Researchers at Northwestern University had two groups of 10 young adults sleep in differently lit rooms. One group slept in rooms with dim light for two nights; the other slept one night in a room with dim night and the next in a room with moderate overhead light — about the equivalent of an overcast day. Participants wore heart monitors at night. In the morning, they did a variety of glucose tests.

Both groups got the same amount of sleep but their bodies experienced very different nights. Both groups responded well to insulin the first night, when they both slept in dim lighting. On the second night, however, the group sleeping in brighter lighting didn't respond as well to insulin. The dim light sleepers' insulin resistance scores fell about 4 percent on the second night, while the bright sleepers' rose about 15 percent. Their heart rates were faster on the bright night, too.

"[J]ust a single night of exposure to moderate room lighting during sleep can impair glucose and cardiovascular regulation, which are risk factors for heart disease, diabetes and metabolic syndrome," concludes senior study author Dr. Phyllis Zee. "It's important for people to avoid or minimize the amount of light exposure during sleep."

From Northwestern's announcement: There is already evidence that light exposure during daytime increases heart rate via activation of the sympathetic nervous system, which kicks your heart into high gear and heightens alertness to meet the challenges of the day. "Our results indicate that a similar effect is also present when exposure to light occurs during nighttime sleep," Zee said....

An earlier study published in JAMA Internal Medicine looked at a large population of healthy people who had exposure to light during sleep. They were more overweight and obese, Zee said. "Now we are showing a mechanism that might be fundamental to explain why this happens. We show it's affecting your ability to regulate glucose," Zee said.

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Sleeping With the Light On May Be Harmful To You

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  • by MikeDataLink ( 536925 ) on Sunday March 20, 2022 @04:48PM (#62375029) Homepage Journal

    And why they posted this story yet again.

    • Lesson learned. No sleeping in the server room.

      • Lesson learned. No sleeping in the server room.

        I have one PC with a blue power indicator light; I put a Post-It over it otherwise I can see the glow at night all the way down the hall in my bedroom. Another PC has a red power light, which is dumb, but not as annoying and doesn't seem to carry as far. Whatever happened to using green?

        • Another PC has a red power light, which is dumb, but not as annoying and doesn't seem to carry as far

          Red light is used in situations where you want to preserve the ability to see something without losing your night vision [straightdope.com]. Militaries around the world (except Russia it seems) use red lights at night when traveling, to see documentation at night or, as seen in movies, in emergency situations where you need to see but regular lights aren't working.

          As the article above states, red light isn't registered stron

    • Third time's a charm?

    • I've also heard that walking around with the lights off can also hurt you. This may have happened to the editors...

    • "Something that has been common knowledge for hundreds of years was just confirmed by Slashdot. Twice"
  • Hopefully this research motivates product designers to stop putting always-on indicator LEDs in everything. Yeah, I know you can just tape over 'em with black electrical tape, but that looks like crap. It's also not always practical to evict all the electronic devices from your bedroom (especially appliances that are intended for comfort, such as a window A/C or humidifier) if your "bedroom" happens to be a dorm or studio apartment.

    • I have a long history of removing bezels and covering LED’s with aluminum foil tape with a single tiny needle hole in it, thus allowing (on close inspection) the light to be seen if needed, but largely blocked. Replace the bezel, and problem solved.
      Unfortunately, things have grown much harder to disassemble without destroying, and the proliferation of LED lights in things that don’t need them (why does my magnetic phone charging cable also need a blue LED in the tip?) make this less of an opti
    • It won't do anything of the sort since this research talks about light that is many orders of magnitude brighter than standby LEDs.

    • I have a mesh WiFi point in my bedroom and was very happy to learn that it had an option to operate without lights, which is configurable for certain times of the day, or to leave it off entirely. Some basic thought into product design can go a long way.

      I was a little disappointed when the pedestal fan I got had bright blue LEDs to indicate that is was on. Like I wouldn't be able to tell from the fact that the fan was spinning. Those promptly got covered in tape. Such a useless feature.

  • Dupes may be harmful to you!

    Stop doing it!

    STAHP

  • I can't believe the human body is so sensitive to so many things. How have we ever survived so many eons without these experts?
    • by splutty ( 43475 )

      200 years ago, people lived less than half our current life expectancy.

      • by pjt33 ( 739471 )

        Life expectancy at birth was low because infant mortality was high. More detailed statistics are needed to make a useful comparison. And the more direct rebuttal to OP is that 200 years ago the only light which might have disturbed most people's sleep was the moon. Candles were precious, and even street lighting was not ubiquitous.

  • The study tested the effect of sleeping with 100 lux (moderate light) compared to 3 lux (dim light)

    That's a lot of light. My home office is about 100 lux with the indirect lighting on. My comfy chair reading light gives me about 50 lux, but shading the light by shifting my head and slightly blocking the reading light drops it to 3 to 5 lux. Printed material is still readable.

    I'm going to have to take my light meter* to bed tonight (watch the dirty thoughts) and check out the pilot lights and TV set in various combinations. I'd be surprised if the TV set throws much more than 3 lux and so according to th

  • Many kids have nightlights in their rooms. I wonder whether the 'effects' are similar for younger subjects? I'd probably assume that it's not important and attributing rising obesity levels to light, rather than decreased exercise and poor diet would be a tough call
  • ... Sleeping with the Television On? https://www.youtube.com/watch?... [youtube.com]

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