[hkmurakami]

Toyota definitely has technology to detect whether the driver is asleep and wake up the driver. (I am not sure if this technology has hit the market yet so I can't comment on what the implementation is)

You can then wake up the driver by actuating the seat or sounding an alarm.

[dakrisht]

Mercedes-Benz has had this technology for maybe 5 years now.

The car will audibly, visually and via haptic feedback through the steering wheel alert a driver if the vehicle detects they are getting drowsy. Nothing new here.