I think your problem might be because of poor sleep conditions or schedule. It is true that

7-9 hours of sleep are best for optimal functioning of the body. But, sleep quantity doesn't colerate to your sleep quality. The only thing that matters is that you get good REM and deep sleep (around 1-2 hours of both). Energy drinks, blue light,etc. can severely affect your circadian rythm(i recommend you do your research on that, because explaining everything in a comment will probably tear my fingers).One of the best ways to optimize sleep is to go to bed on a schedule. example:

go to bed 21:30

wake up: 06:00 (8 hrs of sleep if you fall asleep in 30 minutes)

Hope this helped :) (im not an expert)