I just looked at the newest article in your list ("Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness") and
* there was no mention at all about blue light
* the difference between sleep onset of treatment and control group was 10 minutes - with errors of +-13 and 19 minutes(!), ergo there was no measurable effect.
As can be seen the absolute amount of dark blue to blue (380-500nm) is pretty high regardless of wheather conditions. Full daylight is about 10-20klux, so between 3000lux and 7000lux of blue light alone. For comparison: anti-depression lights are about 2000-3000lux over the whole visible spectrum. Yet people sleep perfectly fine in regions where the sun sets at 11pm in the summer.
There obviously may be an effect, but if it exists, it has to be small.
Those numbers aren't errors--they're standard deviations. The error would be sqrt(N=12), or about 3.5x, smaller, so 3 and 6 minutes, respectively. They also aren't particularly easy to interpret here because it's a crossover design, so the relevant quantity is the change in each subject's sleep onset (or whatever), which is captured by the mixed-effects model, but not the summary statistic.
That said, there are some weird things with the setting: four hours is a lot of reading, and the subjects lived in a fairly dim environment (90 lux) throughout the experiment. Some data (e.g., Chang et al., 2011: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3060589/) shows that the range of exposure matters, so this effect might be minuscule in real life, where the noontime sun exposes people to thousands of lux.
Perfectly right that standard deviations are not the same es errors! Compared to the average effect size, though, in this case they clearly show there's a very high variation in the observed results.
The 4h is really unusually high compared to real-life reading in bed. But compared to the other studies its still quite low! One of the other studies had a whopping 6.5h hours of "bedtime reading".
Right, but the point of the crossover design and mixed-effects model is that some of that variability is attributable to individual differences: you always fall asleep quickly; I toss and turn for a bit.
Imagine you fall asleep in 1 minute normally, but take 11 minutes after light exposure. I take 21 minutes, but 31 after light exposure, and a third person goes from 11 to 21. The standard deviation of each condition is the same size as the effect (10 minutes), but there’s still an effect.
"Exposure to Room Light before Bedtime Suppresses Melatonin Onset and Shortens Melatonin Duration in Humans":
* nothing about blue light
* didn't measure actual effects, just melatonin levels.
"The human circadian system adapts to prior photic history":
* nothing about blue light
* didn't measure actual effects, just melatonin levels.
So zero out of three studies in your link I looked at support the claims. As you posted these studies: Can you point me to a single study from that list that supports your claims?
Interesting. These studies seem to be looking at physical or chemical data. Is it possible that the patterns that people see with evening light are largely mental? Until recently, most artificial light sources used in the home were in the range of 2000K. That could have developed in most people a connection between those color temperatures and sleepyness; one that would not necessarily show up in quantifiable measures like melatonin levels.
Of course, that would need to be studied, and would be a more challenging study, but I think you could probably do it.
This is very interesting. I think a lot of us have come to believe the claim that blue light exposure keeps you awake.
So what do we know? That excessive exposure to any kind of light at night keeps you awake?
It looks like there are several studies on the f.lux page discussing blue light specifically, but fair point that they could be cherry-picking just the studies that support their product.
I have been using f.lux for a decade, since the first version, and it has been a huge benefit to me. So far all native OS implementations simply don't compare. f.lux is doing more than just filtering blue light from the color buffer. They may take donations, but when the project started it was a far cry from the company that exists today and it began with research, as opposed to cherry-picking research after the fact as OP is sort of insinuating.
f.lux and Twilight for Android (inferior but best in class) massively contributed to the reduction of my late night migraines and insomnia.
Try an experiment: code for a few hours late at night with f.lux set to match the white temperature in your room. You can do this by holding up a piece of printing paper next to your screen and matching the color.
After a few hours, change f.lux to the default temperature. Take it as bright as it goes. Then put it back at a temperature which feels comfortable and natural to you. If this is the default color temperature, let me know.
Nobody's saying the affects aren't real or that there aren't benefits. Just that the conclusions are still out on the subject.
BTW, I can program on my computer with super bright neutral LEDS (my preference) lighting up the room and my monitor set to 90 percent neutral lighting, right until bed time and be asleep in 10 mins. Anecdotal evidence is just that, anecdotal.
Some of us are less sensitive to it than others. In particular I am prone to migraines in bright conditions, and on a bright summer day I have difficulty looking at the sky, which will be coated in thousands of bright and distracting microscopic floaters *
And yes, I'm offering anecdotal data-- but I've already provided the relevant studies so this is just a bonus. In my case, the slightest thing will keep me from sleeping. My A/C was out last night and I got scarcely and hour of sleep because of the heat. I am manic depressive and sometimes I will stay up for days if I don't make extra effort to fall asleep. f.lux particularly made a very noticeable difference to me within days of adopting it.
Did you also measure the quality of your sleep, circadian timing, and next morning alertness as well? You're missing out on a lot of the relevant metrics.
If you search for articles and studies on blue light and sleep the overwhelming majority (that I was able to find) say that there is an effect. I posted a number of sources in another comment
