Waterbed of Doom

Have you ever tried to have one of those fancy sleep cycles where you sleep for half an hour, six times a day? Have you found it simply too hard to sleep for only half an hour? Well, nothing will make you get out of bed on time like a bed that slowly smothers you if you stay in it too long.

All you need is to use a full water bed as the mattress, and an empty water bed as the blanket, the two waterbeds connected by a hose. As long as you are between the two waterbeds, water will be forced into the upper waterbed, giving you limited time until you're trapped and can only wait to be slowly smothered to death.

That'll make you sleep polyphasically.