Tim:
It does if you want to suspend/hibernate to the swap space. Your RAM has to dump its contents somewhere, and that's where it goes.
Roberto Ragusa:
Then consider that swap space is not there doing nothing and just awaiting your hibernating. Some of it could be really in use at the moment you hibernate.
Which would be managed by the OS as the system hibernates... And, there's the thing about having *more* swap space than RAM, so there is some wiggle room.