My friend spends hours on the computer while laying down in bed is it depression?

Hard to know: With so little information about your friend, it's hard to know what's happening. At the very least, though, your friend is not exercising his/her body very much and is very focused on the computer. Some of these people have addictions to computer games or porn, etc. Does your friend hold a job or go to school? Does s/he get angry when asked to converse in real time -- instead of computer?