Japanese company Takanoha offers the Nap Alarm, a wearable low-cost gadget that keeps you awake.
The Nap Alarm is placed behind your ear. If you fall asleep it vibrates. The small gadgets determines based on your head movement speed if you actually are about to fall asleep. Pretty nifty - still I recommend stopping to drive and making a break when you start falling asleep. The Nap Alarm sells for 1,450 yen ($12) in Japan.
More details about Nap Alarm or also called Nap Vieeb on the Takanoha & Co., Ltd. site. Via Nikkei BP (Japanese).
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