I can wake up refreshed or more tired depending on how long I napped for. If I decide to take a 45min nap, I usually can't get myself to wake up before 90mins,

I can wake up refreshed or more tired depending on how long I napped for. If I decide to take a 45min nap, I usually can't get myself to wake up before 90mins, and if I have to, I'm super tired like you said. A refreshing short nap that works, is 20 min max, I usually set the timer at 18mins.