Here's my vote. My wife, without really meaning to (she was researching how to teach our kid how important sleep is), found "Garfield's Sheep Shot" - a true gem - at this address. It takes a little while to get used to the controls but works very nicely with the Wii...and the graphics are great, as is the audio!
Here is the link: apparently there are several "sleep" related Garfield games on this site, but "Sheep Shot" definitely rules! Hit Garfield with the sheep to keep him asleep, while blasting Nermal, Squeak and the alarm clock to keep them from waking him up. Can you keep him asleep for 9 hours! Good luck - ain't as easy as it sounds! Enjoy!
http://www.nhlbi.nih.gov/health/public/sleep/starslp/missionz/gamepad.htm