ranjit as someone who is (I'm guessing) decades older than you: I wish I had all this knowledge back then. I have not prioritized sleep my entire life and now, finally, I'm really trying very hard. It's hard to change old habits and attitudes. It's hard not to procrastinate. But you're struggling, you're asking for help, and there's a clear path to improving your learning. Do you want to settle for cramming and a "decent grade" (where I'm sure you forgot most of what you learned right after the exam) or do you want to retain the knowledge and learn it more deeply?
When I had a training at work on different learning styles, they said that some people need micro-deadlines and can't just be given a long deadline and be expected to make progress throughout. They need pressure to be motivated. I think once you're an adult you can't expect someone else to do all the work of setting small deadlines for you but you can do it yourself. Yes, it's hard. I am still struggling with prioritizing sleep and figuring out what strategies work best for me. But I'm trying, and I'm not just saying "I'm a night person" and leaving it at that.
All this to say (and I say this with kindness), don't make excuses 🙂 Oftentimes inertia is a big issue and it's really hard to practice when the lesson is a whole week away, but if you force yourself to sit down for just 10 minutes, you may find yourself staying for much longer. Figure out what works for you, maybe a reward system (video games but only if you practice!) or a different way of thinking. Figure out how to make pressure for yourself, if that's what you need.
For me, I'm really hoping that once I see the results of getting better sleep (feeling great! practicing really well!) I'll remember that at bedtime and put the phone away and eventually it will be my norm.