The Omron Sleepmeter HSL-101 watches you while you sleep. It has a radio frequency sensor that sends out waves over a roughly 5-foot range. It stands by the bedside and starts scanning once you press the "good night" button. The device detects body movements such as tossing and turning, as well as breathing. Blankets won't affect the sensor.

Omron sleep monitor is your bedside sandman

Omron releases a pair of sleep monitoring gadgets that watch you slumber -- Engadget