Sleeping

After struggling with sleep (mainly with falling asleep) for more than a decade, I found out that the brightness and temperature of lights affect the sleep cycle (I used to have florescent lights/daylight bulbs on till bedtime), and so I've made some changes, and here's what's been working for me for the past few years:

3 hours before I go to sleep I dim or switch off every bright light, whether from light bulbs or electronic screens.

-I use secondary lights for the evening: in my work room I have a separate standing lamp with a 6W 3000K led bulb that I turn on 3 hours before bed; In my bathroom I have a pluggable light socket with a 15W bulb (not led); And in my bedroom I have a very dim night-light that I use before bed (There are also similar main/secondary bulbs in the hallway/kitchen/etc.)

-For my PC I use the software f.lux to control the light temperature of the screen (my settings are 4700K for Daytime, 4100K for Sunset, and 2600K for Bedtime).
My monitor's brightness is set to 20% (permanent), and I control my screen's brightness through the control panel of my graphic card: during the day it is set to -10, and an hour before I go to bed I lower it to -50.
(When I used a laptop I set the screen brightness to 30% during the day, then lowered it to 10% at night)

-In phones and tablets there are (generally) built-in settings to automatically control the screen brightness and color temperature based on the lighting in the room and the hour/sunset. Though I prefer to use the app Twilight for that.

-I sleep in a completely dark room (covering led lights from electronics, covering windows with black cling films, etc.).
I also have an air filtering device that creates a white noise by doing so, which might help as well.