I’m sorry to hear you’re struggling with motivation. Something I learnt that starting will often bring motivation afterwards and that is something I experience. When I’m unmotivated I will start with the easy or fun thing that will most of the time get me going and then I’ll want to do the harder thing. So I can reward myself with an easy point.
I also like to set goals through my work being a uni student this is important for me so I can ensure I get my work done while taking care of myself. So if I have a class Monday I like to have most of it done by Friday so I can spend the weekend relaxing or doing the other class work. Or if I have assignments due, I’ll start with the one due first, once I’ve done that I’ll generally want to move onto the next one.
My next tip is breaking it down so for example I have a 2000 word assignment due next Wednesday, I started by doing notes under each heading and then turning them into sentences. The next thing I will do is go back and write the explanation/description (how it relates to the topic). Breaking it down like this helps me clear my head but also if I am unmotivated it still feels like I am achieving something.
Sleep is definitely important is there anyway you could take a break and take a nap or go to bed earlier/ sleep in once or twice week so you can feel less sleep deprived. If you can get the 8 hours a day but I can understand as a student that’s not always possible.
I hope these help.