I have no idea what's wrong with me, I finished high school around a month and a half ago, I used to sleep 6 hours a night and I felt good, I could do things, I could think

I guess my body tried to recover the sleep debt, I now sleep almost 10 hours/day and when I wake up I feel tired as fuck, like I didn't sleep at all
I just want to sleep more

It's okay I guess, I can handle the tiredness, but my brain stopped functioning properly, it's like I'm losing cognitive ability
When someone tells me something, if I don't do it instantly, chances are 99.9% I will forget about it

I can't think properly, I can really feel like I'm dumber then I was 3 months ago

Why is this so, what's going on with me