Depends per person but some people go into deep sleep around an hour, some 45 like you say, etc. Best to just experiment. From personal experience I give my ala

Depends per person but some people go into deep sleep around an hour, some 45 like you say, etc. Best to just experiment. From personal experience I give my alarm a bit more time just because I know it takes me a long time to fall asleep. If going for longer than say 45 though I need a minimum of 2 - 2.5 hours or it will just make things work. But a 2 to 2.5 hour nap can also really make a difference if truly exhausted.