I've been falling asleep uncontrollably (like when changing the tv channel) for about a couple mins to an hr or so & being so exhausted each day. why?

Sleep attacks: There are several possibilities for your hypersomnolence, depending on your nightly sleep pattern/quality, medical conditions, substances/medications. (a) Have you had sufficient sleep in preceding nights? (b) Are you taking any new medications, or do you have a change of your physical/medical condition recently (including pregnancy)? (c) Do you snore, have nasal congestions, or other symptoms?