Dear Diana,
Introduction
I was sorry to hear that you are very stressed before your school exams and can't sleep well. It's understandable to feel this way, but don't worry, I have some advice for you.
Main Body
The first thing I'd suggest is to try and manage your time effectively. Break down your study schedule into smaller, manageable tasks. This way, you won't feel overwhelmed. For example, dedicate specific times for each subject and stick to it. Also, try to incorporate short breaks between study sessions to relax your mind.
Another suggestion is to practice relaxation techniques before you sleep. This could be deep breathing exercises, listening to calming music, or even a warm bath. These activities can help your body and mind to wind down, making it easier to fall asleep.
Conclusion
I hope you find my advice useful. Remember, it's important to take care of yourself while studying. I think that with these steps, you'll be able to manage your stress and get a good night's sleep.
All the best,
(Your name)