Dark and quiet helps with good sleep, as already suggested. (Although I spent most of my adult life with anime/tv on when I went to bed... I think I should admit dark and quiet is better.)
One thing I've been told a lot is not to sleep in the place you spend your whole day. Basically, when you "go to bed," it's good to actually "go." Even if you're in one room all day, maybe try not being in bed - if you have a desk or something - for like an hour before you want to go to sleep.
What time do you go to sleep? Being a NEET might pose some sleep challenges. You may want to add some structure to your day, like a quick exercise at X o'clock every day, or a quiet meditation period, just to give your body a sense of routine.