Laptop Transporting Safety??

I want to take my laptop to school in my backpack/notebook bag. I would certainly use it in the morning, however there are several hours of time throughout the day where I will be in classes where i wouldn't need the laptop or wouldn't be able to use it and would keep it zipped in my backpack.

From traveling from class to class where my laptop would be in my backpack, What state should it be in to protect the hardware components while it's zipped up in my backpack and I'm walking around with it? Obviously I can't leave it on, but which is better for this situation? Sleep or hibernate? I could always shut down but that takes more time to boot up and go through all the routines. Is hibernate safe for transporting and not using temporarily? Also I wouldn't want any heat being produced from the system as it will be in my backpack zipped shut.