I've had this same experience. Sometimes my friends get upset because I'll fall asleep during movies/hangouts and it's like 9pm. I don't really know why I need so much sleep either

I think it partially has to do with what sleep stage you're in when you wake up. If you wake up directly from deep sleep, you're guaranteed to wake up drowsy. If you can sleep a shorter time and take a short nap sometime in the day, that's one possible solution.

That sounds somewhat like chronic fatigue syndrome, which can be a stand alone issue or a symptom of something else. I can't function if I get more than 5 hours of sleep but less than 10-12 depending on the day and sometimes if I over exert myself I need 14+ to be okay. The only 8 hours of sleep that's ever helped me are the midday naps I'd take in high school when i was the most exhausted and burnt out

I have had this issue but for me, it didn't matter how much sleep I got, I'd be ridiculously exhausted during the day and needed naps that were 2 to 3 hours just to function. Once I had my son, I couldn't do that anymore so I was drowning. Finally, I heard about symptoms of narcolepsy and took a chance on asking my sleep Dr about it. I already had sleep apnea and have been on Adderall for over a year. They managed to diagnose me through medication and omgosh my whole life has changed.

Im there with ya i can get full 8 hours of sleep and be exhausted then if i get an hour or two im not feeling exhausted or tired its weird try talking to your doctor about sleep medicine and see if that helps

This is what caused me to go and get my diagnosis in the first place! I was never not thinking about sleep. Adderall was a miracle for this when I started and works a little less now I think but overall it definitely still does! After getting covid, though, this came back full force for two months… Can’t even tell if I’m back to normal yet.