
Blue light may not be as disruptive to sleep patterns as thought: mouse study - rcarmo
https://www.manchester.ac.uk/discover/news/researchers-discover-when-its-good-to-get-the-blues/
======
herf
Michael from f.lux: This research is from a very talented group of
researchers, but it is unclear if it will translate from nocturnal mice to
humans (as others have said). The evidence in humans is mixed, but it either
shows no effect or a tendency in the other direction. There is a study in the
same issue (Spitschan) that says there is no effect in humans.

1\. First, the study does not question the contribution of melanopsin (the
blue-cyan opsin that got everyone talking about "blue light") - it asks a more
subtle question: when you hold melanopsin stimulation constant, what does the
_remaining_ light do and why? Here they are finding whether the cones oppose
or boost melanopsin based on color signals. But regardless of how this works
in humans, we should still expect bright-enough blue light at night to be
stimulating, because of the response due to melanopsin.

2\. Holding the melanopic portion of a light constant is not something we
usually do. For most lights we have today, the "blue" lights would be
considerably dimmer than the "yellow/red" ones if we did this. When we compare
lights of equal visible brightness, the yellow ones are known to have less
effect on human melatonin suppression [Chellappa 2011].

3\. The evidence in humans is mixed, but it actually goes the other direction
(saying blue is more stimulating), or there is no clear effect. In the same
issue, a _study on humans_ by Spitschan found a negative result on whether or
not S-cone contrast has an effect: [https://www.cell.com/current-
biology/fulltext/S0960-9822(19)...](https://www.cell.com/current-
biology/fulltext/S0960-9822\(19\)31501-5)

3b. Other research (in monochromatic and polychromatic light) finds that
humans are _more_ sensitive to blue light than melanopsin would suggest. See a
list below.

4\. We're all still trying to explain how the transition to dusk is
blue/purple, while our own lighting doesn't do that. We have built our
lighting to be relatively bright, but warm. It is not "natural" to extend the
day like we do, but it likely would not help anything to make the lights more
blue, unless they were quite a lot dimmer, or used very novel spectra.

Here is a list of references for the evidence +/\- blue sensitivity (not
melanopsin) in humans:

1\. The Thapan study from 2001 indicates extra blue-light sensitivity in
addition to melanopsin. Lights are seen for a half hour at night.
[https://doi.org/10.1111/j.1469-7793.2001.t01-1-00261.x](https://doi.org/10.1111/j.1469-7793.2001.t01-1-00261.x)

2\. The Spitschan study _from this same issue of Current Biology_ says there
is no effect in either direction when comparing 83x S-cone contrast. The
lights here are "pink" (which has a lot of blue) and "orange" which has very
little. [https://www.cell.com/current-
biology/fulltext/S0960-9822(19)...](https://www.cell.com/current-
biology/fulltext/S0960-9822\(19\)31501-5)

3\. The Brainard 2015 study compares 4000k to 17000k lights: at the same
"melanopic" level the 17000k lights do a lot more melatonin suppression:
[https://jdc.jefferson.edu/cgi/viewcontent.cgi?article=1081&c...](https://jdc.jefferson.edu/cgi/viewcontent.cgi?article=1081&context=neurologyfp)

4\. There is one important study in humans (Gooley 2010) that says we can be
more sensitive to 555nm light after two days in dim light, so that mirrors
this study. But this is not exactly comparable to the study cited here due to
sensitization: it stands on its own due to the duration of the experiment.

It would be interesting if we could find some "truth" to the idea that
twilight colors affect human circadian entrainment - it has been a recurrent
idea for many years. We finally have the technology to target melanopsin
separately from the S-cone (see Spitschan's work for an example).

For the press these results get, you'd be surprised that there has been
extremely little research funding for most of these things in the last ten
years. In a way, I hope that mixed results like these might help! How light
affects us at lower levels, and how different we are from each other is not
"solved" at all, so there is still a lot of work to do.

~~~
oarabbus_
Anecdotally, n=1, etc, turning on Flux at night results in an immediate
release of tension in the eye muscles.

~~~
me_me_me
I am always reminded of it when accidentally I go fullscreen mode and my flux
turns off. It really hits you how bright the screen gets (and I am not using
full filter, I like to keep colour distortion at bay).

Even if the blue light is a myth I will keep on using flux.

------
mgraczyk
Anecdotally, I can pretty reliably trigger a migraine by staying up 2-3 hours
later than normal staring at a normal LCD screen.

With flux/redshift on, that doesn't happen. Blue light may not be keeping me
up, but it definitely fucks my brain up in some complicated way.

~~~
quickthrower2
This could be placebo. Anything related to sleep or headaches there could be a
psychological factor ie because you “know” blue light is bad it becomes a self
fulfilling prophecy.

~~~
OGWhales
I used flux for a long time and thought it was only relevant for sleep. I
found myself using it more during the day as it hurt my eyes less and as a
result I also got migraines and headaches less often. Could be a total
coincidence or even still placebo, just sharing my anecdote.

~~~
internet_user
This is most definitely not placebo.

Blue light is known to cause migraines even in the blind that even lack
cones/rods:
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4939697/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4939697/)

~~~
treeman79
Have migraines. Can verify.

------
OGWhales
This is a study on mice, which from my minimal research appear to be more
wakeful at night. I wouldn't consider this study useful at all in determining
how blue light affects humans' sleep.

~~~
ping_pong
The original study on blue lights was on a small number of humans, and the
delta in sleep was less than 20 mins per night. So if this isn't a useful
study, I would hardly consider the original blue light study useful or
conclusive either. The only reason why you heard about the original study was
because it made the headlines.

~~~
OGWhales
No arguments there.

------
theatraine
Tangentially related: I've been experimenting with very bright lights from
when I wake up to sunset. In my bedroom/home office I have a couple 6000k LED
lights at 8100 lumens making the room almost as bright as noon outdoors. Post-
sunset I use dim red lights. I was inspired by SAD lights but didn't like any
of the ones I tried so went with high-powered "corn" LED lights in normal
fixtures.

I've noticed that I tend to get sleepier at night which is great as before I
would have to force myself to go to sleep (I'm a natural night person.)

I've also noticed a small increase in my distance visual acuity (subjectively
measured by me using an eye chart so not the most accurate.) I have read that
intense outdoor light protects against myopia (see
[https://www.ncbi.nlm.nih.gov/books/NBK470669/](https://www.ncbi.nlm.nih.gov/books/NBK470669/))
so I suspect this is related.

~~~
jiggawatts
I wonder why there's only engineering and so little _science_ in the design of
modern dwellings! A lot of our constraints, such as maximum illumination lux
have gone away thanks to new technology, but the "wellness science" hasn't
been applied. It's not even an established scientific discipline, which is why
I'm struggling to come up with a name for it.

I haven't heard of any large construction company or architect firm focusing
on human-centric attributes such as:

* Minimising the levels of O3, CO2 and CO

* Fine particulate filtering

* Daylight-equivalent illumination

* Red-shifting illumation to simulate dusk

* Noise insulation such as double-glazed glass or weighted foam partitioning walls

* Etc...

In principle, living and working indoors could be _much_ better for us, but
nobody seems to be spending real effort in achieving this.

Instead, everyone is dead set on optimising for square-footage or workers-per-
floor, completely disregarding basic humans needs.

For example, the office of a large government agency where I'm contracting has
atrocious air-conditioning in their main city office building. The
temperatures are over 26C (79F) most of the time, and I get blinding headaches
from the CO2 buildup after a day of bad ventilation. After about 2pm I'm
basically a zombie and can't concentrate. Noone has bothered to do anything
about this for literally years.

(This is not my imagination: Their own staff work in air quality monitoring,
so for laughs they used one of their probes in the middle of our floor and it
basically read "off scale high" on nearly every metric.)

Meanwhile, another building around the corner has floor-to-ceiling glass
windows letting in a lot of light and nice cool refreshing air-conditioning.
There, I can work until 6:30pm regularly without feeling run down.

~~~
teadrivendev
Much of this is covered by The International WELL Building Institute
guidelines, latest version is at
[https://www.wellcertified.com/certification/v2/](https://www.wellcertified.com/certification/v2/)
but it is only slowly coming in as best practice and is a long way from being
compulsory. It doesn't completely cover all the aspects you listed, in
particular - relevant to this thread - it doesn't actually require red-
shifting to simulate dusk - see FAQ #82 on
[https://v2.wellcertified.com/v/en/light/feature/3](https://v2.wellcertified.com/v/en/light/feature/3)

So although you might consider it inadequate, there are certainly people
looking into this and there is lots of science behind it.

------
thdrdt
Here in the Netherlands the use of green light (540nm) is becomming popular
for night lights. It doesn't disrupt sleep patterns of humans, animals and
plants and your eyes can see quite well using less brighter lights (saves
energy). And green LEDs are relatively cheap.

In studies both green and blue light showed to be the least disruptive (but
green is better for night sight). I thought this was strange since it was
always believed that blue light is bad.

But it appears this article agrees.

Edit: a lot of plants and corals are grown under red light. So maybe red could
be more harmful for your sleep if it triggers growth.

~~~
ghostbrainalpha
Green light is also being studied for chronic pain management.

[https://www.npr.org/sections/health-
shots/2019/12/15/7871389...](https://www.npr.org/sections/health-
shots/2019/12/15/787138928/researchers-explore-a-drug-free-idea-to-relieve-
chronic-pain-green-light)

I struggle with migraines and am going to do a big Green Light experiment in
my house for 2020.

------
pilif
For the last 3 years, the most reliable way for me to fall asleep quickly has
been watching youtube videos on my phone. Night-shift is off too.

Seeing how differing everybody's experiences seem to be, maybe this is one
thing where people are just different from each other.

~~~
papito
You don't have to watch them. Just the blinking of TV will distract your brain
from racing. That's how I do it. In my case, I rewatch something that I
already know by heart - Seinfeld, futurama, etc. If I know the plot, I don't
get into it enough to be awake.

~~~
sethammons
I'm on the opposite side of the coin. My brain recognizes any conversation on
a left-on TV and "turns on." If I was asleep, I'm about to not be. It is
especially bad when I know the episode or movie as I start to pre-quote lines
in my head and, shit, now I'm awake.

~~~
throwno
TV programs are designed to get your attention. Try watching college lectures
instead. I'm still not sure what Russian formalism is actually about, but boy
it sure is a great sleep aid.

------
m104
They only tested on mice. Mice are nocturnal.

------
georgebarnett
A few weeks ago I was advised by a lighting specialist that there’s a lot of
ongoing disagreement regarding the best approach for reducing how light
affects sleep. I was aware that there has been limited research and many of
the solutions to this point have been basically “copy flux”.

Thanks for posting this. Very interesting read and has made me change my
buying behaviour.

~~~
34234lr
Is there disagreement also regarding the lighting level? I have dimmable
lights and I like how I feel when I gradually dim them to darkness before
going to sleep.

~~~
georgebarnett
I don't know; I was particularly looking at color shifting devices and the
recommendation was to hold off on the purchase for a few years until the
science had a change to settle.

------
kerkeslager
One possibility is that some people are more reactive to blue light than
others. For me, the blue light versus non-blue light difference is really
striking.

Another issue is that, as others have noted, a lot of people's experiences are
with Flux, but Flux is an incomplete solution to the blue light problem. I use
a Macbook Air: Flux changes the color temperature of my screen, but directly
below my screen is a backlit keyboard which is very, very blue. It was a big
turning point for my sleep health when I got a pair of blue light blocking
glasses which handled this in addition to the screen blue light.

~~~
soapboxrocket
Did you get the glasses because you believed they would help your sleep, or
for other reasons? One solution to why so many people talk about the
improvements with Flux or glasses could be a simple placebo affect.

~~~
34234lr
True, but placebo effect is random and uncorrelated with the change. Otherwise
big pharma would just replace all drugs with sugar pills.

So for placebo you should also have a lot of people reporting that "greenish
screen" helps, and you should have a green option in flux.

~~~
soapboxrocket
As @kerkeslager states below, this is just not true.

I think the best way to understand a placebo effect is this: If I don't give
100 patients a drug to cure a cough and 30% stop coughing, I have a baseline.

If I give 100 patients a drug to cure a cough and 90% stop coughing I can say
my drug is effective.

If I give 100 patients a sugar pill and tell them it will cure a cough and 60%
stop coughing I can say this is better than my baseline and the placebo effect
is present.

If I give 100 patients a sugar pill and tell them it will cure a sneeze and
60% stop coughing and nobody stops sneezing, then I need to revisit my
previous study to find out if sugar can cure a cough. But in this case you
don't have a placebo effect because the patients believed the pill was to
address a sneeze.

------
decebalus1
The title should probably be edited to include 'in mice'. If it's
editorialized, it should be done right. Mice sleep during the day, they are
nocturnal. I would trust sleep studies on mice way less for extrapolating to
humans... I mean, it's great that this is studied. But they should probably
use apes.

Also, waiting for all the anecdotal comments 'Yeah, it makes sense. Best sleep
I get is after I use my devices without f.lux' to flow.

------
tengbretson
Performing this study on humans seems like it would be incredibly easy. Why
even bother with mice?

------
kev009
Not sure how much conditioning this is but I tend to be more focused and task
oriented in >4000K color temperature. I can't really stand residential
settings >2700K (unless it's some isolated work room like a garage, laundry
etc). So the people that work on that lighting design stuff seem to know what
they are doing, at least for me.

It doesn't help with the desire to actually go to bed, but another anecdote is
the darker the room the better the sleep. Most window dressings are decorative
and designed to be somewhat translucent. Add a blackout cellular shade or
curtain. Eliminate any displays, cover power LEDs etc.

------
macinjosh
I use blue filters more for comfort reasons than for health reasons. For me it
is less harsh looking and it just let's me work for longer.

------
chadlavi
Are mice a good analogue for human circadian rhythms?

~~~
coldtea
Better than ad-hoc hand waving, as is the "theory" most "blue light
prevention" products are sold by...

------
pdimitar
Anecdata:

The night modes of my displays (iMac, MacBook Pro, iPhone, iPad) definitely
help me be a bit more relaxed compared to staring at them in their normal
mode, especially during the nights.

That being said, reduction of blue light does not help _that_ much either. I
found that a much stronger contributor to my staying awake is the light of the
screen itself. I found that if I am in the mood to nap during the afternoon,
the smaller difference between the my phone's display light and the ambient
light helps me fall asleep much, _much_ quicker compared to when I am staring
at my phone with all lights turned off. The difference is much more pronounced
and obstructs my brain's desire to doze off.

So IMO the reduced blue light has an effect. But it might not be that big
indeed.

------
Ericson2314
OK intuitively there is indirect and direct sunlight. Based on my highly
unscientific personal experience I'd guess the body can tell between direct
daylight and sunset spectra (both warm) and indirect daylight and twilight
spectra (both cool). Electronic blue lights after lots of f.lux seem quite
annoying, so I'd guess they are more like daylight.

Relatedly it always bugged me when I was little that blue lights seemed "white
in the middle with turquoise then finally blue exterior". Blue lights just
couldn't be both bright and saturated very easily. I wouldn't be surprised
this is related to the daylight-ness vs twilight-ness.

~~~
34234lr
Direct/indirect daylight is not warm, is cold:

> _Daylight has a spectrum similar to that of a black body with a correlated
> color temperature of 6500 K_

[https://en.wikipedia.org/wiki/Color_temperature#The_Sun](https://en.wikipedia.org/wiki/Color_temperature#The_Sun)

~~~
Ericson2314
Ah, all the better. So the day is neutral/cool or quite cool (direct or
indirect) and the evening is warm or that twilight blue which
[https://www.flickr.com/photos/bob_81667/25663810348](https://www.flickr.com/photos/bob_81667/25663810348)
is just the same indirect thing but darker?

Would seem like coolish is any time of day depending on brightness, but warm
is definitely evening.

~~~
nightfriendly
When the sun goes down, colour temperature is determined by the alternative
light source. For most of the past 100,000 years, life on our rotating planet
has relied on moonlight (cold) or firelight (warm) to see at night.

Incandescent lights (Edison light bulbs) are a bit cooler than the candles and
(most of the) oil lamps they replaced.

Bright cold (high Kelvin rating) lighting at night is a very modern invention:

Temperature (K) Source

1,700 Match flame

1,850 Candle flame, sunset/sunrise

2,700–3,300 Incandescent lamps

3,000 Soft White compact fluorescent lamps

4,100–4,150 Moonlight,[2] xenon arc lamp

5,000 Horizon daylight

5,000 tubular fluorescent lamps or Cool White/Daylight compact fluorescent
lamps (CFL)

5,500–6,000 Vertical daylight, electronic flash

6,500 Daylight, overcast

6,500–9,300 LCD or CRT screen

15,000–27,000 Clear blue northern sky

~~~
Ericson2314
By "twilight" I meant the atmospheric scattering from the sun just over the
horizon. Is that roughtly same color temperature as the "5,000 Horizon
daylight"?

------
Waterluvian
Lots of good comments on the quality or compatibility of these results for
humans. But I'll add: I don't care. Even the placebo effect of the night time
mode on my screens has a calming effect and signals the day is winding down.

~~~
Semaphor
I agree, blue light, close by (so my monitor more than the TV) does make me
feel more awake. Could be placebo, could be trained behavior (as in red light
makes my body think sleep), could be that this study is not transferable to
humans. Or any combination of these :) I'll happily stay with f.lux :)

------
tabtab
Blue light is the new caffeine:

    
    
        2010: Study says caffeine is unhealthful 
        2011: Study refutes 2010 caffeine study
        2012: New study says caffeine is unhealthful 
        2013: New study says caffeine is safe
        2014: Etc.

~~~
lonesword
"Unhealthful". TIL that it's an actual word.

~~~
tabtab
[https://www.merriam-webster.com/dictionary/unhealthful](https://www.merriam-
webster.com/dictionary/unhealthful)

"Harmful" is probably a better choice, now that I think about it.

~~~
Izkata
You got me curious: [https://www.merriam-
webster.com/dictionary/unharmful](https://www.merriam-
webster.com/dictionary/unharmful)

------
davidmurdoch
I reliably get restless leg syndrome when there is a blue LED left on in an
adjacent room with its light leaking in to my bedroom. Other triggers: too
much caffeine late in the day and dehydration.

The yellow LEDs in the room don't bother me when I forget to turn the device
off. And the red clock projected onto my ceiling doesn't bother me either.

I used to sleep fine with blue LEDs though, so maybe it's just different for
different people, ages, environments, and/or other factors.

------
nixpulvis
I wonder how a human raised in a home with incandescent vs fluorescent vs
other colors of light bulb would react. I have to assume this is at least
partially a learned response.

------
StuffedParrot
I’m curious if they tested the wavelengths that wood fires give off as well as
moonlight—this would most closely match “natural” light exposure post
twilight.

------
squarefoot
It may not be disruptive to our sleep patterns, but surely I find extremely
annoying if abused like it is today. At over 50 I have no sleeping problem, at
least not more than I had before the digital age; blue light just make me
nervous, and I recall hating blue leds thrown in every appliances just because
they're dirt cheap long before people started talking about any potential
harm.

------
mgazzer
Hmm this makes me wonder what did our previous generation of computer people
do that had all this evil blue light blasted into their brains?

I feel like this is the new "wellness" science that sounds good in practice,
but lacks evidenced based studies.

~~~
lonesword
My guesses:

1\. The previous generation did not have laptops.

2\. The previous generation did not nearly have as many
programmer/hackers/<late-night-computer-user-moniker> as we have today

3\. Because of #2, nobody cared if a really small percentage of the population
lost sleep due to blue light?

~~~
djmips
I feel you've forgotten phones. A majority of people have a phone that they
can stick in their face in bed.

------
vlunkr
However the science turns out, I still recommend flux/redshift just for the
reduced eye strain. I don't even bother with scheduling it to shift throughout
the day, since I've never noticed any impact on my sleep.

------
n1vz3r
It may be "not as disruptive" for sure, but since I began to use night light
mode both on my phone and laptop, I began to fall asleep in 10-15 minutes
after going to bed. Also I use warm light LEDs intstead of cold ones.

------
zarkov99
Anecdotally, it is definitely highly disruptive to me. I have red light
shifting in all my devices and I bout some blue light filtering glasses and
that does make a difference in how quickly I fall asleep.

------
rationalfaith
Anecdotal experience and of many others, go against this "experts".

As all things, it's a spectrum but the press has to be sensationalist about
it.

------
tingletech
My eye doctor told me to use a blue cutting program all day long (not just at
night) to save my eyesight

~~~
bluegreyred
My eye doctor told me that it's all made up by the optometric industry and
there's no meaningful evidence.

(I still use night mode and calibrate my screens for low temperatures because
even if it is just a placebo, it works for my comfort)

------
aszantu
Do mice eben see blue? They only see greyscale, or am I wrong?

------
art4ur
The red light doesn't seem to travel as far. It's less likely to wake your
partner when you peek at your device in the middle of the night.

~~~
internet_user
that has to do with two things:

1) our photoreceptors in retina have highest sensitivity to blue

2) blue photons are higher in energy than red (1.5x to 2x, depending on
specific frequencies/color temps)

------
princekolt
...in mice.

But sure, let's drop this tiny snippet of information, after all it will drive
clicks, am I right??

------
xchip
TL;DR: “Our findings suggest that using dim, cooler, lights in the evening and
bright warmer lights in the day may be more beneficial.“

------
384028345
OFFTOPIC: Isn't blue light still best to be avoided as much as possible, as it
damages cells in the eye, causing macula degeneration. Please correct me if
I'm wrong.

~~~
theothermkn
[https://www.health.harvard.edu/blog/will-blue-light-from-
ele...](https://www.health.harvard.edu/blog/will-blue-light-from-electronic-
devices-increase-my-risk-of-macular-degeneration-and-blindness-2019040816365)

This is widely debunked. The above is but one of many such counterpoints.

------
moron4hire
As a society, we like to focus on presumed "easy" fixes. It's not the
sedentary lifestyle, chronic sleep deprivation, and massive amounts of
caffeine we drink that disrupts our sleep, no, it's the _color of light_.
Never mind that the effect is apparently so small that science has yet to
prove conclusively that it even exists, this is the thing that is killing
everyone.

------
quotemstr
The number of high profile research reversals over the past decade or so has
been extraordinary. At this point, I'm forced to regard most published
findings as simply false unless strongly supported by intuition and repeated
studies. More and more, I feel like the process of science has decided all the
"signal" the natural world is giving us and that now we're just interpreting
noise, at least as it pertains to studies on people.

~~~
thrower123
There's an astounding amount of nonsense popularized in mass media where they
take the results of these studies and promote it as the gospel truth, without
noting the caveats - tiny sample size, only studied in mice, effect sizes,
etc, etc. By the time the game of telephone has relayed the story to the
public via the local TV news puff piece, it has been distorted so heavily that
it becomes complete nonsense.

