Your Hamster may have Diabetes, thats what happens when they have too much sugar in their diet. As a result they wee alot, they may loose some fur, they sleep alot more.
If you want more info on Diabetes visit:
http://hamsterhaven.forumakers.com/s...-issue-t73.htm
Hamsters can die from this- so make sure you feed the Haster plenty of veg and a bit of boiled egg.
Get your Hamster vitamin drops, as that will help.
What breed is your Hamster?
Mainly, Russian Dwarf Hamsters suffer from this anyway, and if that's the case it's not you fault.