top | item 30680939

Light exposure during sleep impairs cardiometabolic function

276 points| sndean | 4 years ago |pnas.org | reply

122 comments

order
[+] synaesthesisx|4 years ago|reply
This article refers to "moderate" (100 lx) light exposure - this amounts to an overhead light on in the room for the entire duration of sleep.

I would say an overhead light is a significant amount of light, but wonder how low the threshold is for sleep disruptions. Living in an urban environment, there's a non-negligible amount of ambient light that makes its way in. I don't use a set of blackout curtains, but I know several friends that say it makes a real difference.

[+] scruple|4 years ago|reply
> I don't use a set of blackout curtains, but I know several friends that say it makes a real difference.

Maybe a year ago, I was planning on having a sleep study done. At some point in my 30s I stopped feeling like I was recovering when I slept. I decided, however, that there were some things that I could work on improving before having a sleep study.

Most of what I addressed falls under sleep hygiene: Blackout curtains, better sheets, better blanket/comforter, better pillows, a better mattress, a sleep mask, reducing noise. It took a while to sort all of this out. "Better" is also subjective.

I also slowly worked on getting to bed earlier. I used to get into bed around 11:30pm. Now I'm in bed between 9:30 and 10pm. I read a little bit and then sleep. I stopped having calories after ~7pm.

We have young children, too. 3 under 3. I sleep very well now. Despite the regular interruptions I actually feel like I am getting the highest quality sleep of my adult life right now.

The blackout curtains, though... The difference they made from one day to the next was immediately obvious. My wife and I both woke up feeling more refreshed, looked at each other and said, "Why did we wait so long to do this?"

[+] Terry_Roll|4 years ago|reply
> I don't use a set of blackout curtains, but I know several friends that say it makes a real difference.

Have blackout blinds on every window upstairs so thats its dark enough during summer mid day sun to sleep. They keep the heat out during the summer (to the point I dont need the air conditioning on albeit on the hottest days and the warmth in during the winter which contributes to energy saving, the only downside is the air gets stagnant in small buildings.

I believe a lot of German homes also have external blinds over their windows for similar reasons plus they offer a layer of security making it harder to break in, but then what do the Germans know?

100lux is quite bright, I have a lux meter and here in the UK 100-200lux is a really cloudy winters day level of brightness, where as a bright summertime day will exceed tens of thousands lux for comparison.

Its because light affects the release of melatonin black out blinds are fitted. Melatonin increases the release of stem cells and stem cells play their part in repairing the body, but like I say earlier, CO2 levels building up cause the body to be stimulated even during sleep so sleep is not as refreshing as it could be in small homes and almost all UK homes are small, but hey the CO2 helps contribute to an increase in GDP and thats all that counts!

[+] exeldapp|4 years ago|reply
I don’t live in an area with a lot of light pollution but have black out curtains for full moons and that hour or two after sunrise before I’m awake and they have made a noticeable difference.
[+] Someone|4 years ago|reply
> This article refers to "moderate" (100 lx) light exposure

I think that’s relative to daylight, which already is 1,000 lx under an overcast sky, 10,000 in full daylight, 100,000 in full sunlight.

[+] lm28469|4 years ago|reply
> Living in an urban environment, there's a non-negligible amount of ambient light that makes its way in. I don't use a set of blackout curtains, but I know several friends that say it makes a real difference.

God bless Europeans and their cutting edge roll shutter technology, I can sleep in total darkness despite the street lamp 10m away from my bedroom window. And ye[, it definitely makes a difference.

[+] jbverschoor|4 years ago|reply
Pilots are only allowed to stay in hotels with 100% blackout curtains
[+] owenversteeg|4 years ago|reply
The research discusses 100 lux for one whole night, which is quite a lot (indoor levels range from 100 to 1000 lux, outdoors from 10k on a cloudy day to 120k with direct sunlight at noon.) Like others here, I’m curious about other strengths of light - I assume up to 0.1 lux is fine, as moonlight is typically 0.05-0.1 lux, but what about between 0.1 and 100 lux? And what about light exposure during part of the sleep cycle? There’s quite a lot of sleep research, much of it poor quality, so I’d be grateful for any specific study suggestions.
[+] gehwartzen|4 years ago|reply
I noticed that on nights the full moon was shining though the regular curtains on my bedroom window I would get a horrible nights sleep. It wasn't fixed until I got blackout curtains.
[+] erosenbe0|4 years ago|reply
One night? You could probably repeat this experiment with fart stench or any other obnoxious irregularity and find impairment of glucose tolerance at a decent p value.

I see the headlines now: "Fart stink during sleep impairs cardiometabolic function." So yeah, guess the wife is getting diabetes if I don't move to the dog house.

[+] makeitdouble|4 years ago|reply
Joking (?) aside, cheapish air purifier are reasonably efficient to help for stinks and other air issues during sleep if they have a carbon filter (IKEA ones have the option for instance). Bonus point if they can auto-adjust power depending on the air status, but I don't think that's mandatory.
[+] social_quotient|4 years ago|reply
I find these stickers helpful for a ton of little lights in the bedroom

LIGHT DIMS Black Out Edition - https://www.amazon.com/dp/B009WSN8PK/ref=cm_sw_r_cp_api_glt_...

[+] ad404b8a372f2b9|4 years ago|reply
I use electrical tape to cover those and it's made a world of difference, it's crazy how many items have LEDs in them. Power strips, clocks, monitors, charger cables, my synth, ... My girlfriend thinks I'm nuts because I'll get up in the middle of the night to tape over previously undiscovered LEDs.

What do we need all these LEDs for?!

[+] dylan604|4 years ago|reply
Grabs wheel, jerks hard left:

Oh my those are some fun images! The art on a lot of Amazon listings are just hillarious. Some are down right creepy. The 6th image for this listing has a very intersting bit of text on the screen in what I'm guessing a slide in a deck??? My favorites are the ones where the "product" is just photoshopped in with Escher level physics required to make it believable.

[+] isolli|4 years ago|reply
It reminds me of this article [0], a very interesting read on "surviving" winter in Sweden (and Northern latitudes in general). It ends with how in summer things are flipped and everyone complains about how poorly they sleep.

[0] https://www.ft.com/content/180f3428-1923-11e9-b93e-f4351a53f...

[+] soderfoo|4 years ago|reply
Before moving to Sweden,I was fully aware of short Scandinavian winter days. They're like the poster child for seasonal depression.

Nothing/no one prepared me for the sun rising at 3 am in May... It was quite an interesting first year.

[+] Beltiras|4 years ago|reply
I live in the north part of the north hemisphere. It's bright outside the entire 24 hours for almost a month during summer. I use a sleep mask to combat it and the last 5 years I feel like I regained sleep during the summertime. Last year I purchased a Manta Sleep mask and they are next-level good. Total darkness and really easy on the face. I have no affiliation with the brand, just a really happy customer of theirs.
[+] hobbescotch|4 years ago|reply
In the summer if I don’t sleep with my mask off I start to feel myself slowly unhinging. Sun being out at 2am while you’re trying to sleep can definitely make you feel out of it! Hard to find blackout curtains that work perfectly too.
[+] rendall|4 years ago|reply
Could this effect be explained otherwise by "disruption of normal sleeping environment"? Presumably all of these people are used to sleeping with dim lights. What would the effect be on subjects who were used to 100 lux light?

My intuitive sense is that light at night has some harmful effect. On the other hand, I live at a latitude where summer nights are very bright, and I and my fellow residents generally get used to it. Perhaps the effect diminishes?

Are there people with sleeping habits such that they would find darkness similarly disruptive?

[+] kingcharles|4 years ago|reply
Ugh. When I was in jail I had to have a bright light shining on my face every night for five years. Cover the light and you went to the Hole.
[+] rootw0rm|4 years ago|reply
At one of the jails I was in the deps would put the dayroom TV on at full volume all night long when they were pissed at us. between that, no pillows, and 3:45 AM breakfast, sleep hygiene isn't terribly valued in county
[+] vaylian|4 years ago|reply
The laws should be updated to include a right for dark sleep conditions, because we know now that this form of treatment is effectively physical harm.
[+] tomcam|4 years ago|reply
Been there, done that, don’t want the T-shirt
[+] bolangi|4 years ago|reply
Hope this discovery will influence hospital lighting policies.
[+] Broken_Hippo|4 years ago|reply
Hospitals have slightly different constraints.

You - as a patient - often have time to sleep unlike in your daily life. And the hospital is often going to wake you up nonetheless: It is, generally, more important to take your vitals than it is to allow you uninterrupted sleep.

They also need to look out for safety. You have a bunch of patients who are feeling poorly. Some aren't quite sober due to pain medications. All in an unfamiliar setting. A bit of light makes it safer to move around at night if you should need to. Sure, a patient can control lights, but not everyone will be able to. In some areas, you are sharing a room, too.

All that said: For my last hospital stay, the room got as dark as I wanted at night - but I'm not sure that would have been the same during the summer (I can read outside at night during the summer).

[+] Dove|4 years ago|reply
I always bring a sleep mask and ear plugs with me to the hospital. It confuses me that they don't hand them out! Sleep is essential for healing. I have often had nurses in hospitals tell me to sleep, but I've never had a nurse offer me ear plugs.
[+] westurner|4 years ago|reply
Research on Blue light and sleep: https://justgetflux.com/research.html

https://en.wikipedia.org/wiki/Melanopsin :

> Melanopsin photoreceptors are sensitive to a range of wavelengths and reach peak light absorption at blue light wavelengths around 480 nanometers.[30] Other wavelengths of light activate the melanopsin signaling system with decreasing efficiency as they move away from the optimum 480 nm. For example, shorter wavelengths around 445 nm (closer to violet in the visible spectrum) are half as effective for melanopsin photoreceptor stimulation as light at 480 nm.[30]

Under Melanopsin > infobox > "Biological process", e.g. "entrainment of circadian clock by photoperiod" and "regulation of circadian rhythm" are listed.

[+] giantg2|4 years ago|reply
I even hate laptop/modem/smoke detector lights.
[+] jimmux|4 years ago|reply
There was a time when it seemed like every new device had to have an always-on blue LED. Escaping blue light at night was an effort. These days small white LEDs are in fashion, which I find much more tolerable.
[+] MrFoof|4 years ago|reply
You can buy some self-adhesive light attenuating film. They sell it in pre-cut shapes, in black (several strengths), white and silver. The name brand that started it all was, "LightDims".

I put them on... most things. Network gear LEDs. Power LEDs. All manner of things.

[+] toomuchtodo|4 years ago|reply
Eye mask. Try it, it is fantastic.
[+] lobocinza|4 years ago|reply
I have RGB memory that is really bright and light the whole room when lights are off. It was cheaper than a similar non-RGB when I purchased. Guess I will put same electric tape on it as I already did with everything else.
[+] sliken|4 years ago|reply
Some duct tape (to block) or a sharpie (to decrease the brightness) does wonders.
[+] echelon|4 years ago|reply
I love studies like this. I know, I know. "It's just a study." But it means that people are having new thoughts about how the body responds to its environment and enters into chronic disease states.

Some of our "new ideas" about diseases are actually maybe not all that crazy [1].

Every time I see one of these potential connections, my brain jumps to generate new hypotheses for everything around it. I sometimes wish I was a PI looking into these things.

For instance, this article made me think that perhaps children being exposed to night lights upsets their metabolic behavior in early development enough to lead to long term neurotransmitter dysfunction and desensitization. ADHD. Just a hypothesis. Totally unsupported. Probably not a contributor. But I'd love to have access to journals and data and test these things.

In a different life...

[1] https://news.ycombinator.com/item?id=29882347

[+] 11235813213455|4 years ago|reply
Recently I started to only work in daylight times, I had to shift my sleep 3-4 hours sooner. The idea is to never need to use artificial lights, wouldn't work well in high latitudes winters though :))
[+] CamelRocketFish|4 years ago|reply
I’d be interested to know if this is because of light hitting the eyelids or light hitting any part of the body.
[+] lizardactivist|4 years ago|reply
What worries me is that some of the research done on this suggests that even tiny amounts of light could have a noticable effect, like green and blue LEDs on common home electronics when it sits in standby or sleep mode.
[+] Tepix|4 years ago|reply
Are there similar studies that cover the effects of noise during sleep?
[+] Sxubas|4 years ago|reply
Is not the test population too small? (n=10) or is there any reason we can generalize this with such a small number?
[+] whiddershins|4 years ago|reply
I wonder if regular exposure means the body adapts.

These participants likely were acclimated to sleeping in a dark room.