If you're talking about borosp1's post about electronic light, that's actually really good advice. I was having a really hard time falling asleep a few years ago, which was causing a lot of trouble in my life because I was constantly tired the next day, and the doctor told me no flickering light sources within 60 minutes of going to bed (things with a refreshing screen like a smartphone, laptop, television set, etc.). It actually helped out quite a bit. The reason why is primarily because the flickering light sources emulate the sun to your brain, which delays melatonin release, so your brain stays wired in awake mode rather than drifting off into sleep mode.
If you're having any trouble falling asleep at a reasonable bed time, that's something that helps me out a TON actually.