Light exposure during sleep impairs cardiometabolic function | Hacker News Reader

Light exposure during sleep impairs cardiometabolic function

pnas.org

276 pointssndean122 comments

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.

> 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?"

+1 for the blackout curtains. Easily 20% better sleep.

And our only source of light at night prior was a street light outside our bedroom window.

Blackout curtains are great for sleeping, but I have trouble waking up and getting out of bed when the room is still completely dark (when it’s light outside in the AM).

Recently bought some Hue smart lights to simulate sunrise with blackout curtains which is helping. Next up, motorized blinds that open at a scheduled time.

(#firstworldproblems)

Living in Seattle, having lights that turn on in the morning really help wake me up in the winter months. I use an Alexa routine which turns on NPR and turns the nightstand lights to ~50% so they’re providing light but not harshly so.

Accidentally set up android's new gradually lit screen alarm, and it really made waking up quite nicer. The kind of "oh wow, so simple yet so nice" feeling when it happens.

I live in the arctic, and black out curtains in the summer is a must have (as it's daylight 24/7 for a month). And around december it's dark 24/7, so a sunrise lamp helps a lot to wake up naturally and not feel like total crap every morning.

Here in Germany they have metal shutters that vertically descend and black out all light and sound. It’s common on most windows.

They are permeated with little holes that allows light and sound in if they have not fully descended. If they have then the little holes are folded shut.

I’ve found the same issue where if they’re completely down waking up is hard, so I leave the top two rows of holes open to let in natural light.

I think having a small amount of light gradually filtering in helps a bunch to wake-up.

Video of shutters - https://m.youtube.com/watch?v=_KePLmie7lE

> Here in Germany they have metal shutters [...]

Small correction: not metal, these are (mostly) made out of plastic nowadays, sometimes aluminum, and earlier, from wood.

But yes, the effect if they aren't fully closed, is nicely adjustable to limit light without making a room pitch fark.

I'm living in Germany and my wife really likes shutting them fully. That really makes it hard for me to wake up. I wish I could automate them. 2 problems: We don't own the flat we are living in and I wouldn't even know where to start hacking these fully closed electronic systems.

I think you are looking for something like this. https://www.jalousiescout.de/gurtwickler/elektrische-gurtwic... I believe most tool stores (OBI, Bauhaus) have them. At least here in Austria.

I live in France and we have the same shutters (metal plates rolling vertically with th esmall holes that can be uncovered).

I automate what I can at home - the CHO (Chief Home Officer - my wife) mostly disapproves because of some weird concerns about reliability (70% of availability for lights is that I call great, but opinions vary).

There is a simple solution for the shutters - you can use a Shelly 2.5 (https://shelly.cloud/products/shelly-25-smart-home-automatio...) that you connect in parallel to the shutter. It works wonders if you have a manual switch on the wall and probably with a remote too (I specifically asked for a manual switch on the wall). You can program the device itself to open the shutters at, say, 10 minutes before sunrise or whatever. You can easily remove them when you leave your flat and reuse somewhere else.

The Real Solution For Real Hackers (c) is to use Home Assistant (https://www.home-assistant.io/). <flamewar on> Do not settle for inferior systems such as jeedom, domoticz, ... </flame war off please do not hunt me>

> and I wouldn't even know where to start hacking these fully closed electronic systems.

If you have electronic shutters, most of these are a simple 230V based system: one neutral line and two 230V inputs, one for each direction. Hacking them is easy, get two programmable 230V relays (e.g. use a Raspberry Pi relay board) and never ever activate both relays at the same time.

My Apple Watch actually starts brightening up before the alarm goes of to 'simulate' some light. My Pixel phone before also had that, works quite ok

You Germans have them too? Good! In Spain we have used them since forever, but it seems that most countries have yet to discover their wonders. They are one the things I miss the most when living abroad or traveling around.

Same here in Greece. I have no idea how people sleep without them, visiting the UK or US is always frustrating because I have to wake up at the crack of dawn.

I just moved to a new flat and, by design, the motorized shutters don't close fully and the top two or three rows of "holes" remain exposed when the motor disengages.

I was a bit annoyed at first and considered tweaking the mechanism to close the shutters fully, but in the meantime the impact this tiny changes has made on my and my girfriend's sleep patterns is tremendous and now I think I'll leave it that way.

We used to be very late sleepers, I work from home and regularly wouldn't wake up until 11AM or so. Now at 8:30 sharp I'm awake and ready to get up. It's a pleasant way of waking up too, I can tell that my body is sort of meant to be woken up that way instead of using an alarm sound. Obviously it also means that I get tired much earlier at night. But overall it seems like a positive change, especially since I'm in my mid-thirties and it's not like I regularly party all night anymore and I appreciate getting more time to do stuff in the morning.

> They are permeated with little holes that allows light and sound in if they have not fully descended. If they have then the little holes are folded shut.

This too is a bit generalised, as ours do fully close. In fact they actually snap into place to activate a break in barrier. This makes it harder to break in, as they can not be easily pushed up or removed.

Rolladen? Yes, I remember those! My wife and I lived in Belgium at the time, but we visited her sister and brother-in-law in Germany on a few occasions.

Yes, I want! Have wanted for years, in fact. Hard to get here in the US, however.

I've had great success with Wake-up Lights / Sunrise alarm clocks. They do get quite bright when fully lit.

Hue smart lights simulated sunrise was a game changer for me.

When I wake up and realize that in the morning, all I get for light is out of a smart-bulb, I get inexplicably depressed.

I did buy the motorized curtains. It is quite expensive, but works pretty well. I'm really happy about them, nothing beats natural light to wake up.

I got SwitchBot Curtain for a simple DYI motorized curtains project. Affordable and trivial to install. I let the light in 10 minutes before the alarm. Should've got it sooner.

I've always wondered why both "sunrise lamps" (like the one you're referring to) and "light-therapy lamps" (i.e. lamps of 10000+lm with a diffuser) exist, but there are no sunrise light-therapy lamps, which 1. go from dim to holy-wow-that's-bright on a slow timer, and 2. which are designed in a shape where you could fit them around your bed somehow. (IMHO, they'd ideally be a flat ceiling panel!)

Have you tried a sleep mask? Once you lift it off the room will be light again.

I found that to help quite a bit and as a bonus they are portable and much more economical than motorized blinds or blackout curtains.

That being said motorized shades do seem pretty neat and may have a privacy advantage depending on where you live.

Would you say the blackout curtains made a bigger difference than the sleep mask?

Not OP, but had the same experience several years ago. The answer is yes.

If you want a cheap test, you can tape aluminum foil over your bedroom window(s) for a night (learned this from The Martian!). It will fully block all light, and you probably already have what you need to try it in your home. Note that it does have the downside that from the outside you look like a crazy person.

I also use this trick when traveling - some AirBnBs have crazy thin curtains.

Huh, that's kind of wild. I'd assumed that blocking all light out at your eyes would do the same trick, I'll have to try the blackout curtains. Thanks!

I use a mask too, but it moves around when I sleep. Even properly positioned I haven’t found a mask that doesn’t leak around the edges.

I have this problem, too. I've tried probably a dozen masks, the best was one that I got overseas in Southeast Asia and it has no branding, etc.

Your face structure may be different than mine but I found this sleep mask stays put and works well at blocking out the light — https://www.amazon.com/gp/aw/d/B07D3M5TTZ

Yes, definitely, but I continue to use the mask. There are times when I need the mask, because I'm napping or sleeping some place that isn't blacked out, and if I haven't worn it in a while it is very bothersome / distracting.

My wife was complaining about waking up in the middle of the night. I grabbed some black out curtains. She woke up the next day feeling better than she has for a long time.

Turns out there was a streetlight that would hit her in the face and was causing her to wake up. We didn't realize it until we got the blackout curtains.

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.

Pilots are only allowed to stay in hotels with 100% blackout curtains

In searching to attempt to find corroboration for this factoid, literally the only things mentioning pilots and blackout curtains I could find were your own comment here and a random forum post from a pilot saying blackout curtains don't really work. Nothing about any requirement that pilots only be placed in hotel rooms with blackout curtains.

Not true that there is any sort of official rule to this effect. I've slept in a lot of crew hotels that had only semi-decent curtains.

It is true that well-behaved airlines, who take an active interest in fatigue prevention, do try to book hotel rooms with blackout curtains and good sound proofing. This is however not a universal behaviour and not all destinations where layover is necessary have any hotels with these qualities.

> 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!

> 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.

Pretty incredible how well our eyes can move between these completely different scales of brightness like its nothing.

> 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.

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.

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.

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.

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.

I agree -- our bedroom is small and benefits from even a simple filter! However, my point was to humurously criticize the study title for sounding too conclusive. The study is useful as a starting point but it is pretty well known in such literature that one-night of introducing variable X can yield results showing negative short-term perturbations. X can even be something generally regarded as positive such as first night on low-stress vacation, or even the first few times people share a room with a partner. Changing a routine increases vigilance (not sure of proper technical vernacular for that, but you get the idea).

> One night?

https://www.nosleeplessnights.com/first-night-effect/

> First Night Effect

> When people spend a couple of nights in a specialist sleep clinic to check for sleep disorders, sleep experts have long known they can’t always rely on the first night’s data.

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_...

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.

Certainty

Elegance

Professionalism

Just Like You

My mom always told me I was certainty

If only I had more time, I'd love to gather up these images with these fake words and create a dictionary. I know that there are thesewordsdonotexist type of sites, but this seems different. Luckily, I have no free time to find myself down that particular rabbit hole.

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?!

> I use electrical tape to cover those

Another easy solution is to add a layer of nail polish to dim leds.

Yeah and why isn't there a switch to keep them always off, on everything!

Because a switch costs an order of magnitude more than an LED.

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...

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.

Yes, the article resonated with me because I lived in Berlin for 4 years. When your child wakes up at 4 am and the sky is bright blue outside, it's impossible to put them back to bed!

Same, for Finland. The movie Midsommar really captures the mood of endless sunlight.

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.

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.

Easyblinds Blackout Blinds or Blackout EZ works well for me. (Basically, lightproof textile velcroed all around the window frame.)

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?

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.

Been there, done that, don’t want the T-shirt

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

Were we in the same jails?!

I think this shit is universal across county jails. Prisons get more litigation, but jails are hard to litigate in.

I fucking hate no pillows, 3AM breakfasts.

I sued and got the breakfasts legally changed to 6:30am. That got me another 10 days in the Hole.

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.

That would be nice. Proper nutrition would be great, too.

The Effects of Vitamin-Mineral Supplements on Serious Rule Violations in Correctional Facilities for Young Adult Male Inmates: A Randomized Controlled Trial

<https://journals.sagepub.com/doi/10.1177/0011128721989073>

Hope this discovery will influence hospital lighting policies.

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).

Hospitals are really there for downside mitigation and acute care, not necessarily for “recovery”. If you take that perspective, it makes a lot more sense why the lights, beeps, vital checks, loud talking in the hallway, etc all conspire to ruin your sleep. Ultimately, getting healthy enough to be discharged and getting back home is when/how you’ll fully heal.

Source: Spent a few nights in hospital a week ago and came home covered in bruises and sleep deprived —- but very alive and ready to recover!

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.

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.

I even hate laptop/modem/smoke detector lights.

Eye mask. Try it, it is fantastic.

Could you suggest one? Maybe one that doesn't uncomfortably push your eyeballs in

As a generic statement, look for a silk sleep mask.

While not often actually silk, they tend to be soft polyester and use fabric filler rather than near-credit-card-grade plastic. (I agree, I don't understand firm sleep-masks)

In the photos (I know they're photoshopped these days), look for the mask to actually wrap around the user's face, and look for photos that show the same material on both sides (so you can see that you're not getting a different material on the user's face-side). Look for a bit of gloss to the material so that it appears to be a nice silk-or-polyester. Look for the little plastic clip of an adjustable elastic loop so you can adjust the tension.

I definitely have had to play with the elastic tension to get a soft fit.

Edit: better example: https://smile.amazon.com/Adjustable-Lightweight-Comfortable-...

An almost-meets-the-cut-example-but-might-have-matte-fabric: https://smile.amazon.com/ZIMASILK-Natural-Adjustable-Super-S...

A generic search: https://smile.amazon.com/s?k=silk+sleep+mask&crid=1X69JJEXPF...

I have heard that, since polyester is carcinogenic, it’s unwise to have things in your bed or near your face for long periods of time that are made mostly of polyester. I would be a little concerned about a sleep mask sitting on my eyes and near my nose and mouth for 1/3 of my life.

Do you also avoid polyester clothes?

I do indeed. I primarily only buy cotton for that exact reason. Rayon is even worse.

Second the silk eye mask, one of the best things I've ever purchased.

We use these and are very satisfied.

https://www.amazon.com/dp/B07PXB4NZB/

(no affiliation, just a satisfied user of the product)

Search amazon for ‘contoured eye mask’. They are pretty comfortable.

I use this: https://www.amazon.com/dp/B07KC5DWCC

+1 to this one - I use it too. It really helps if you use blackout curtains in addition to it. Add in earplugs and some white noise source (I use a fan) and you can solve a large portion of your sight/noise problems at night.

I cut off the sleeve of an old fleece pullover. Works great as night cap and eye cover.

(I previously used a sleep mask bought on Amazon but found it slipped off too often. Also, the straps irritated my ears.)

I love my nite hood exactly for that reason: https://www.nitehood.com/

This definitely qualifies as one of those things I often wonder "what were they smoking when the thought of this, and where can I get some?". I'd love to be a fly on the wall in pitch meetings or see The Sharks be pitched this. However, I love that you can just wake up in your nitehood, adjust to be on the on the go, and one more adjustment to rob the stage coach or money train with your gang of outlaws.

I remember several twitter threads about this and the clear winner was usually the Manta Sleep Mask. Doesn't push your eyeballs in, plus the eye parts are velcro-attached to the strap so you can adjust them to your face.

Tried maybe around 5 eye-masks in my usage of them during the last 7 years and the best one that does not fall off during sleep(mostly), does not let much light in and is comfortable: https://www.aliexpress.com/item/1005002554825105.html?spm=a2...

Had good luck with this one. Stays pretty dark even during the middle of the day:

https://www.amazon.com/gp/product/B08ZHJMCQD/

I've tried probably a dozen over the years and settled on this one about a decade ago:

https://www.hibermate.com/

I've had three in that time due to accidentally leaving it in hotel rooms.

A test of a good mask is if you can see any difference with your eyes open or closed, and if you can feel your eyelashes touch anything if you open and close them. These are excellent and have a satin outer which slides around the pillow rather than coming off or moving.

They include ear pads to block out sound, but I find them a bit uncomfortable and never use them.

Those never work or feel comfortable for me. I just throw a tshirt over my head, works great

I find that the pressure on my head over the course of a night, even with the fairly loose mask, is very uncomfortable and disrupts my sleep even more than the lights.

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.

A big of black gaffers tape takes care of that for me. Electrical tape in a pinch. If I use white gaffers tape, it significantly cuts the light but is still visible when I'm looking right at it.

How many people outside of production work a) knows what gaff is, b) where to get it, c) uses it with a pair of scissors?

Search "tape with no residue" on Amazon, Gaffers will come out. That was how I knew it.

How to search for gaffers tape without typing "gaffers tape" :D

Hold my tower pc.

https://www.amazon.com/s?k=tower+pc+case

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.

Are you really trying to sleep in a room with that type of LEDs, or do you just really hate all things LED?

When I was a student I slept with everything I owned in a single room. I had to block light from the Ethernet port status lights on my computer and printer, the smoke alarm, and my phone charger.

These days I own a home with far more space. The things which have LEDs are not in my bedroom.

Or just use a little electrical tape...

Some duct tape (to block) or a sharpie (to decrease the brightness) does wonders.

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.

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

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 :))

That's a pretty bold statement that nightlights are associated with obesity.

But there's a theory blue/white reduces melatonin output.

So, use red nightlights, apparently true red wavelengths don't affect sleep.

https://www.healthline.com/health/why-not-to-have-red-lights...

I’d be interested to know if this is because of light hitting the eyelids or light hitting any part of the body.

Maybe related: Morning and Evening Blue-Enriched Light Exposure Alters Metabolic Function in Normal Weight Adults

https://pubmed.ncbi.nlm.nih.gov/27191727/

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.

Are there similar studies that cover the effects of noise during sleep?

Is not the test population too small? (n=10) or is there any reason we can generalize this with such a small number?

I wonder if regular exposure means the body adapts.

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

Another thing to worry about during those situations where your sleep-environment is not optimal.

Reminds me of how studies found out that, when sleeping with lights on, one gains weight.

I wonder if enough overly bright device LEDs scattered around a room would hit 100 lux

N=20

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