How restless are you really at night?
Do you get better or worse sleep when you sleep on your back?
Do you stop breathing at night? And for how long?
Professional sleep studies can answer those questions (the most expensive hotel rooms you'll likely sleep in, and room sevice is limited :), and so can some expensive take at home sleep study devices.
But why not do this yourself with an arduino board, and linux?
This talk will show how to repurpose an arduino board to record your body position throughout the night as well as your breathing patterns, wirelessly upload that data to a linux machine via Zigbee, and process that data to see how your night went.