Not that it's relevant in hammy's case, but there's this neurological condition called idiopathic hypersomnia. Unmedicated, those of us with the misfortune of having this disease can sleep upwards of 16 hours a day. Prior to meds, I slept 15 hours, was up for 2 or 3 hours, and then napped for another three hours. Why? Leading theory (backed up by research) is an overproduction of GABA and problems with reuptake.  Debilitating condition, not a choice. Hammy is just lazy, though, since I never got fat.