The Nomad Nine Wireless Anti-Sleep Driving Alarm works on the principle of electronic balance and does not interfere with normal movements in the car.

The alarm sounds only when the driver's head falls forward in drowsiness; simple but effective. The alarm will sound at the preset angle.

If the driver's head drops forward far enough, the alarm sounds off. This position at which the alarm will sound can be adjusted. For example, if your normal driving position is with eyes and chin pointed down, the device can be set to tolerate that, but will sound if the chin drops below a certain level.

A gravity switch inside the alarm monitors the position of the driver's head. The Wireless Anti-Sleep Driving Alarm is about the size of an external hearing aid and is very lightweight. It fits snugly around one ear and will stay in place even if glasses are worn.