Drowsy Driver Detector

A recent Gizmag article reports on a "smart cap" that monitors worker fatigue by measuring brain waves.  This washable cap has a waterproof sensor built into its lining that calculates the wearer's level of alertness every second and transmits this information via Bluetooth to a device that can display this information or sound an alarm when a critical threshold is reached.  While I've seen articles about other inventions marketed to help detect and/or awaken drowsy drivers, it seems that an approach as potentially accurate and unobtrusive as this one could potentially one day become a standard safety feature in vehicles of the future.