If you could wear a headset that watches your eyes to track your tiredness, and then alerts you to stay awake, would you? No we probably wouldn't either. But the technology could be useful when inevitably bought out by Google for Glass.
Vigo is currently a Kickstarter project for a Bluetooth headset that tracks your eyes and can alert you when nodding off with LEDs, vibration and sound. The device connects to your smartphone via Bluetooth so you can control its sensitivity to your blinking and the alert types you want.
The ability to tag events like driving or studying could be useful, since these are the situations it seems most helpful in. Or, crazy idea, you could just sleep more. We're just saying.
The Vigo device - at the time of writing this - costs $79 on Kickstarter and is at $38,000 of its $50,000 goal. If this proves successful we'd be surprised if it lasts long before Google buys it. While the idea could be useful we can't see anyone wearing that thing just to stay awake. As part of Google Glass on the other hand, that's more likely.