Comp health

I'm no computer noob but I have been wondering exactly how long a PC should be left on and if going for long periods of time without turning it off(to rest so to speak)hurts how long it'll last in the long run. I guess I just want to know from someone who knows more in that area than I, if I should turn it off more than I do to preserve it's functionality. This is 4chan so I'm on it of course a lot, but I don't usually shut it down before bed.

you can leave it on forever, just shut the monitor down to prevent burn-in if you have a crt.