f.lux
Do you use your computer in the evening or at night? If so, you are disrupting your sleep schedule by exposing your eyes to bright light and blue colour-waves. f.lux automatically changes the tint of your computer or phone screen to help you with your sleep, removing bright blue light. Make sure to specify your exact location and f.lux will automatically adjust your screen settings in the background as time progresses. Do not be alarmed by the orange tint you'll notice with a lack of blue light. You will get used to it so well that disabiling f.lux will remind you how your original screen colours are keeping you awake.
I recently decided to use this program to help with insomnia.