I watch students push themselves beyond their limits every year only to realize they have yet to find their true limits. If you're feeling burned out because you've pushed yourself, good job! You young'uns can take it. It'll come in handy later in your life and all it really means is that your potential has yet to be found. Keep your grades up & push through.
As a general rule, don't sleep in - get some exercise instead.
Personally when I'm burned out I resort to one of three things:
1.) Video games like Kerbal Space Program.
2.) A robotics hobby of 3D printing obscure flying drones for air-worthiness.
3.) Check out e-books from the local library on philosophy for my career (current read:
Who Owns the Future?). Usually I progress at least a chapter before bed.