Blue light is exactly what it sounds like, light that is blue, with a wavelength of about 450-495 nanometers 3/pic.twitter.com/wYZGqUxYDQ
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So what about all the blue light blockers? Well, there are plenty of studies on those too The problem is that they're mostly not very good 14/
For example, this recent study took 14 people, and gave half blue light filtering glasses and the other half normal glasses They found some barely significant differences (p=0.035-0.049) It's not enormously convincing stuff 15/ https://www.sciencedirect.com/science/article/pii/S0022395617308592 …
A 2017 systematic review could not identify a single study (!) of appropriate length and duration to make any statements about blue light blockers either way 16/pic.twitter.com/YzcjziwUvC
Do blue light glasses work? Currently, best evidence suggests they probably don't do that much, but the best evidence is really not good 17/pic.twitter.com/qD4NoAcWNr
To sum up: - Blue light might be bad - We aren't sure, it might not be - Blocking blue light might help - It also might be a total waste of time 18/pic.twitter.com/9OwkhF122S
Best bet seems to be that blue light blocking software/glasses might improve your sleep a little, but it's hard to know if there's a real benefit to your health there 19/
This is particularly true given that many of the studies are unblinded and rely on self-reported symptoms, which makes them MUCH less reliable as evidence 20/
Podcast now out on this topic and recent headlineshttps://soundcloud.com/senscipod/episode-7-blue-light-glasses …
New smaller RCT showing sleep starting 20 min earlier https://www.eurekalert.org/pub_releases/2019-05/esoe-spi051519.php …
I cover that in my just-released podcast 
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