Om – Why my doctors told me that if you are going to spend inordinate amount of time in front of a computer screen at night, you might have tough time going to sleep. The screen-flicker makes your eyes and your mind think it is day time, hence you have trouble sleeping.
If you drink too much coffee, you are going to have trouble sleeping. If you don’t sleep your heart works longer hours and has to pump more blood and is under stress. Problems get compounded when you are a smoker, are overweigh, lead a sedentary life (phone/computer) and/or are on a plane constantly. Link.