(Michael from f.lux): this kind of thing is necessary for most buildings, because otherwise people don't get a "day" signal when they spend time indoors. Most of us spend >90% of our time inside.
However, we shouldn't mess with light levels like these (or even somewhat lower ones) without some limits, and the main one is some automatic timing to turn things down after it gets too late. Otherwise you will find yourself staying at work later and later each day, and it's no accident.
Our clocks don't work that well with more than about a 14-15 hour photoperiod ("day"), so spending 18 hours under 5000 lux will screw up your overall rhythms, making your internal day longer than 24 hours and reducing your sleep. This is considerably worse if you're a natural night owl - it will make you later, faster.
The myth of electric lighting is that we can live in a permanent summer and turn the wintertime into summer, but there are important seasonal questions that we should think about too. For instance, cancer progresses much faster in summer than in winter [edit: cancer progresses much faster in constant light: winter vs. summer is complicated], and the winter schedule even engages a different part of the central clock in your brain than the summer schedule does. There are some important things going on here, which we've mostly tried to remove from our environments.
Knowing how the body works and having the capability to change it really do need to evolve in parallel - I think there is way more capability than knowledge right now.
Is there any solid peer-reviewed, published papers on this stuff? While it sounds intuitively correct and attractive, I've struggled to find anything rigorous that shows light colour and intensity in the evening has an effect of sleep quality - its all anecdotal.
The general field of study is called chronobiology. Doing a search for "chronobiology light sleep" gives all sorts of results. One example:
> Environmental light synchronizes the primary mammalian biological clock in the suprachiasmatic nuclei, as well as many peripheral clocks in tissues and cells, to the solar 24-hour day. Light is the strongest synchronizing agent (zeitgeber) for the circadian system, and therefore keeps most biological and psychological rhythms internally synchronized, which is important for optimum function. Circadian sleep-wake disruptions and chronic circadian misalignment, as often observed in psychiatric and neurodegenerative illness, can be treated with light therapy. The beneficial effect on circadian synchronization, sleep quality, mood, and cognitive performance depends on timing, intensity, and spectral composition of light exposure. Tailoring and optimizing indoor lighting conditions may be an approach to improve wellbeing, alertness, and cognitive performance and, in the long term, producing health benefits.
I live in Norway. While I'm below the Arctic circle, summer nights are bright. I don't need outdoor lighting to read as the sun goes juuuust below the horizon. This time of year, days are short and the light intensity never really gets all that bright. I don't have issues with any of it - and I'm an immigrant.
There are many genetic differences, even within a given ethnicity, concerning sleep. What may impair sleep for one individual may have no effect for another. This variation may have been beneficial from an evolutionary standpoint, because variable sleep schedules meant that someone in a given community could always respond to threats.
Have you considered manufacturing f.lux for home lighting, such as a wall-mounted controller for Hue or Ikea bulbs that changes color spectrum depending on time of day? Or possibly bulbs with f.lux build in, so no external controller is required?
Yes, we were looking at this quite a while ago. Lighting is a really hard business (especially residential) so we did not make the leap, and mainly have tried so far to work with people who are in that business.
We thought back then that some form of "smart lighting" would be universal. This mostly hasn't happened, so the truth is that the opportunity is different than we had guessed. Today most "smart" replacement lamps are $20+, similar to several years ago, even though normal lamps are $1.
We do support a lot of integrations with f.lux on Windows, so people can use f.lux with their Hue/LIFX/yeelight/etc., but it is somewhere <2% of our users right now.
Out of curiosity, what makes lighting such a hard business?
I have given the issue some thought as well. f.lux integration with Hue is great, but unfortunately not a solution for me, as I'd have to keep my windows pc running all day.
There are apps, such as iConnectHue, which are able to install a preset on the Hue Bridge that dims the lights or changes the color temperature without needing any computer or phone turned on when the timer fires.
The fact that bulbs are 1. small and 2. run on mains electricity is a big complicating factor. By far the easiest way to build this would be with dual-colour LED strips. But that's not how most people want to light their homes.
I think it's the cost. You can make a cheap driver off 120V that looks like shit and has terrible thermals.
A solid driver with good filtering and good thermal characteristics is expensive. So you're left with a $15 LED bulb that sits on a shelf next to $5 bulbs, selling to customers who see nothing other than two LED bulbs where one is grossly overpriced for no reason they can comprehend
As a software developer, the fact that I even have to build custom electrical hardware is a significant barrier.
The fact that this hardware runs at 120v (or 240v in my case) makes it the barrier higher as there's now a chance that making mistakes might kill me.
Additionally, the high power levels mean that adequate cooling is needed, and as a non-expert it's hard for me to know whether I've done that correctly.
While possible (there are tons of "blue filters" on the play store), the effect will always be considerably worse that with root access, since apps can only display overlays, not change the screen's white balance.
Btw, if you don't insist on using f.lux and have root access, take a look at cf.lumen: It allows much more precise configuration (I have it remove almost all blue in sleep mode).
I have some Osram Lightify bulbs along with Home Assistant to do this.
During the day time all my bulbs are at 6000K and 100% brightness, at 6pm the bulbs in my bedroom/office dip to around 4500K and 50% brightness, and at 8pm to 2700K and minimum brightness (we have a toddler).
In my kitchen/living room during the day it's the same, at 8pm to 4500K at 50% brightness and at 11:30pm to 4500K at minimum brightness.
I considered having the schedule run on when the sun sets, but in my location that is 10pm in the summer and 4pm in the winter so it doesn't really work at the extremes (I have the same complaint with tooks like f.lux as well :D).
I've been looking for a hardware solution to this problem so long.
I would kill to have like a programmable dimmer knob that can progressively adjust both temperature and power set to a fixed temperature and power at start (ie: 3750k at 100%) and finish (ie: 2500k at 10%) positions then it auto-calculates the right spot in-between.
I did it with a Pi, HomeAssistant, smart bulbs, and some Python, but it was not as good or as reliable as I'd like.
I wanted the lights to know what temperature and brightness to turn on to based on a schedule, but there wasn't a way for them to pull the desired state upon power-on; instead I'd have to detect power on and push a state change to the desired color temp. This meant they'd turn on at whatever last state they had on power-off, and a few seconds later (or frequently much slower) adjust to scheduled color temp.
This may have worked better had I used smart switches to turn lights on/off rather than wall switches that cut power to the bulbs, but I also had issues with the smart hub losing connection to bulbs occasionally, HA not reliably seeing power-on events for the bulbs, and HA losing connection to the hub. (Bulbs/hub were Ikea tradfri; perhaps other manufacturers' products are more reliable).
This was a couple years ago; I haven't looked into it much since - maybe it would be easier to do now.
Phillips makes a bulb that does this with those temperatures almost on the mark. I put them in every fixture in my home and got lutron casetta smart dimmable switches. Drops to 50% at sunset and 20% at bedtime.
Hey Michael, thanks for commenting! (And thanks for making f.lux which I've found incredibly useful for years!)
I strongly agree that it's important to change light levels throughout the day; it's very obvious that bulbs this bright suppress my sleepiness. I should probably add this to the post's FAQ so that people don't do anything irresponsible.
I do think that some people might get a mistaken impression of how strong the evidence is when you claim that "cancer progresses much faster in constant light" without citing or caveating that this is based on one study, in rats, where the treatment shone a light on them for a full 24 hours.
> Our clocks don't work that well with more than about a 14-15 hour photoperiod ("day")
Regarding only natural light, what would be the ideal latitude region for psychology year-round?
At 30°N and 30°S days swing between 10 hours to 14 hours through a year. Would it be ideal to live in between 30°N and 30°S, or would you expand/shrink the range?
ps. Any resources on geography-psychology relationships would be appreciated.
SAD and cancer rates go up somewhat with latitude, definitely by 35-40N. But it is complicated because it doesn't affect everyone the same way. e.g., most of Europe is living above 40N.
In some cases, availability of natural light (due to tree cover, weather, and position in timezone) is as important as latitude.
I would guess that some people are simply better at living at more extreme latitudes or with a weaker circadian signal. Several researchers have tried to use particular genetic markers to explain this, but I don't know a specific one that explains all of it.
These are pretty bold claims. I'm not sure if a single communication from 15 years ago is enough to to build such a relationship. Please note, that any claims about "cancer" in general are hard to make, because they have such variety of phenotypes.
I made a note about Blask's 2005 work below, which is the main work I was thinking about. We can say that constant light is bad for cancer.
But as I'm refreshing my memory, winter can cut both ways. For some, it makes more darkness and more melatonin (which is thought to be protective of cancer). For others, winter results in not seeing enough light, and so melatonin amplitude goes down. And so this is associated with increased cancer.
Hey Michael, first off I love f.lux and use it every day. I have a question relating to your comment: is there any reason not to have an extremely high lumen smart light fixture which progressively dims throughout the day and syncs with the solar cycle in the user’s area? That seems like the holy grail, and is simply a combination of Philip’s Hue/LIFX tech and the bulb in the OP.
Yes, I think that's right - we have 20,000 lumens in our office and it is pretty cool, except you can't see your screen when it's up all the way. I still prefer daylighting, because it changes the angle of the light and everything else through the day.
A couple things: I don't think you necessarily need more light in the morning if you have a well-defined (artificial or real) sunset, and if you've reduced light at night to a lower level.
We add light to the morning so that we can add as much light as we want at night - the two cancel out. But I think it would be better to really try to design the evening to look different than the workday. Lights should change, and they mostly don't.
There are for sure some people with long internal clocks (DSPD/N24) who need very custom lighting schedules to have a normal schedule, but I think if we make the overall signal stronger (more day to night contrast), a lot of the differences between night owls and early birds would become smaller.
They are using these underground to help simulate the true daylight experience. Basically a smart led version of a traditional roof sunlight: https://www.youtube.com/watch?v=aJ4TJ4-kkDw
"Yes, I think that's right - we have 20,000 lumens in our office and it is pretty cool, except you can't see your screen when it's up all the way."
Can you elaborate ? 20k lumens doesn't seem like that much ...
I see residential interior decorating guidelines at about 20 lumens per square foot for non-intense areas like living rooms[1], etc., which implies a 1000 sf office (smallish) conservatively lit with 20k lumens.
I just put 11k lumens of background lighting in a 400sf living room and I am worried it's a bit under-lit, given 12 foot ceilings.
I think that perhaps you are talking about something different than I think you are ?
[1] As opposed to kitchens where I see 50-80 lumens per square foot recommended...
My office is not that big, so yes it is quite intense there. But, I should say just that system is capable of delivering >500 vertical melanopic lux (which is a metric based on holding the meter vertically rather than pointing "up"), and this feels remarkably bright.
I think the seasonality data may be mixed, with more diagnoses in the fall and spring in human subjects studies.
This particular claim was a hypothesis from Richard Stevens, with some experimental work that shows rapid cancer growth under constant light (in human tumors implanted in mice) by Blask (2002, 2005): http://www.nel.edu/userfiles/articlesnew/NEL230802A03.pdf
The main mechanism in the Blask work is thought to be suppression of melatonin.
The rat study you cite here is certainly far from sufficient evidence to make such bold claims or implicated that indoor lighting can promote cancer development in humans! I think you should edit your statement in the top comment further to make it clear that you are not referring to any solid human data here at all.
Thank you for f.lux, I enjoy coming home early, being with my family then working later in the night. Having f.lux installed on my computer has improved my quality of sleep tremendously
However to tie it to the article : do you know of the variability between individuals of lighting effect on morale ? I know a lot of people getting depressed when winter comes, but it has 0 effect on me
I love f.lux and I've used it for years, however I have to bring up the one feature I dislike...the "alarm clock" type feature which supposedly could be turned off by an option, but in reality there was no option to turn it off. I was able to turn it off on one computer but not the other, both windows OS!
Are there any lamp brands you can recommend that allow me to set the bulb temperature, but that don't require an internet connected hub and app on my phone? So RF or something.
(I've been meaning to try them out but haven't done so yet, so I can't vouch for the quality in detail. Their stuff is usually solidly mid-range and very good value for money, though.)
A lot of them have very strict routines about going inside and using super-dark curtains at particular times. I've gotten to email some people above 60N and it is just what they do.
In the old Aschoff "bunker" studies where people allowed to keep the lights on as long as they wished, they concluded the human clock was 25.1 hours. We know this isn't true if you provide a proper light-dark cycle, it's much closer to 24. But I treat this old work as a cautionary tale - we can be 25.1 hour animals if we leave the lights on all the time.
I grew up at 66N (Northern Iceland), for what it's worth blackout curtains are rare to nonexistent there in my experience. Sometimes bedroom curtains don't even cover the whole window, and during parts of the year it's daylight outside 24/7.
When I've traveled there with foreigners who grew up at more southern latitudes with year-round "normal" day/night cycles I've sometimes had to tape black trash bags to the bedroom windows for their benefit.
What do the locals do? We simply get used to sleeping in daylight. One way of doing that is getting used to sleeping on your back with one of your arms across across your face and over your eyes (such that your elbow is between your eyes/on your forehead and the back of your palm touches or is near the opposite shoulder).
I still sleep like that out of habit at more southern latitudes out of habit, and a quick poll among some fellow Icelandic expats where I live when this came up the other day revealed that they do too.
In Spain we have lots of problems and room for improvement in many issues, but one thing I can be proud of is that the vast majority of homes have blinds that close completely and get zero light in. I often wonder why it isn't like this elsewhere, and especially in northern places where it would be especially convenient (I get that it's possible to adapt, but wouldn't it be nicer to be able to sleep in any position?)
Of course, the problem with this is that I'm totally spoiled and when I travel abroad (1), I can almost never sleep well. Hotel rooms in most countries have blackout curtains but if you're used to Spanish blinds, even those let a lot of light in from the edges. And don't get me started about LEDs...
(1) PS: Now that I come to think of it, I don't sleep well when I travel within Spain either... curiously, people's homes have blinds but hotels typically don't.
I'm assuming you're talking about the exterior metal curtains common to Spanish houses (persiana con cajor exterior [1]).
Those are only incidentally to block out light, they're mainly for thermal management. You put them down in the middle of the day to keep hot air and direct sunlight out.
A system like that is completely unsuitable in places that get snow. If you installed it on a house in Iceland it would at best freeze solid, and more likely explode as snow slush made it into the joints and froze solid. You don't even need to go outside of Spain to see that, go up to Monachil in Granada and see that no house in the area uses that system.
Of course you could install blinds like that behind double-glazed glass, but at that point you can just buy normal blackout curtains. Since you don't need it for thermal management (any amount of external heat making into the house being a luxury) there's no point in installing it on every window in the house.
So then for practical purposes you're left with only installing blackout curtains in the bedroom, but if you live that far north you're going to need to just get used to sleeping in the light anyway. What are you going to do if you go on a camping trip where you sleep in a tent and forget your blackout eye mask, just not sleep?
As far as I know, they are for both purposes. In fact, most of them can be lowered enough to provide thermal insulation but still let light through (they have small horizontal holes for that purpose), but if they are lowered more, the holes close and they block light. So it's definitely a planned feature, not a side effect.
In most of Spain they are installed outside of the window glass, but in the north they are installed inside, so they are protected from cold and wind. As in this picture, for example (just found at random): https://www.inmoatuel.com/piso-exterior-de-90m2-reformado-a-...
But they still seal the window hole perfectly so they block light much better than blackout curtains. I suppose the problem with Monachil is that it's a cold place, but within Andalucía which is generally warm, so they don't have a tradition in the area of installing blinds inside as is the case, for example, in Galicia, where you can definitely see them even at high altitudes where snow is common.
When I go on a camping trip... indeed I just don't sleep well, I'm afraid :)
The picture you linked to is taken in A Coruña whose mean temperature is around 10 degrees higher[1] still than relatively mild[2] climates near the arctic circle.
I didn't mean to suggest they weren't also used to let light in. I've spent a lot of time in houses that have these installed, letting light throughout the day while keeping the house relatively cool is a constant balancing act. I meant that without the need for the thermal management you'd go for other sorts of systems, such as internal blinds.
I.e. I'd expect that in places like A Coruña you'd use these for thermal management in the summer with the outer windows open, whereas in Iceland there's maybe 1-3 days of the year where the outside temperature is anywhere near the inside temperature.
I live at 59.3 and dark curtains are not too common, most house I saw have some kind of shades or fluffy curtains, both don't block light
> they concluded the human clock was 25.1 hours
You keep quoting questionable or out dated research, the 25 hours figure seems to be wrong [0]
> Early research into circadian rhythms suggested that most people preferred a day closer to 25 hours when isolated from external stimuli like daylight and timekeeping. However, this research was faulty because it failed to shield the participants from artificial light
However, we shouldn't mess with light levels like these (or even somewhat lower ones) without some limits, and the main one is some automatic timing to turn things down after it gets too late. Otherwise you will find yourself staying at work later and later each day, and it's no accident.
Our clocks don't work that well with more than about a 14-15 hour photoperiod ("day"), so spending 18 hours under 5000 lux will screw up your overall rhythms, making your internal day longer than 24 hours and reducing your sleep. This is considerably worse if you're a natural night owl - it will make you later, faster.
The myth of electric lighting is that we can live in a permanent summer and turn the wintertime into summer, but there are important seasonal questions that we should think about too. For instance, cancer progresses much faster in summer than in winter [edit: cancer progresses much faster in constant light: winter vs. summer is complicated], and the winter schedule even engages a different part of the central clock in your brain than the summer schedule does. There are some important things going on here, which we've mostly tried to remove from our environments.
Knowing how the body works and having the capability to change it really do need to evolve in parallel - I think there is way more capability than knowledge right now.