Head-worn sensors have been tried in a variety of form factors including headbands, helmets, headphones, glasses, and goggles. Now a group of Polish inventors, forming San Francisco-based IntelliClinic, are crowdfunding a new twist: a brainwave-sensing smartphone-connected sleep mask.

The device, called NeuroOn, has already raised $330,000 on Kickstarter, more than three times its original goal. It's a foam sleep-mask that contains several different sensors and a Bluetooth transmitter. It offers users several different ways to use the data it collects. The mask contains an electroencephalographic (EEG), or brain wave, sensor as well as sensors that measure the movement of the users' eyes and facial muscles.

The data is collects on sleep patterns is meant to help users adapt what's called a polyphasic sleep schedule, a theory that suggests a person can sleep less overall by sleeping in carefully timed short spurts throughout the day. But the NeuroOn creators stress that the mask is also useful for standard sleeping. It can function as a "smart alarm," waking the user immediately after a certain number of completed REM cycles with gradually brightening LED lights. The creators also claim that the device can help a user recover from jet lag or induce lucid dreaming.

When the mask is not being worn, it sends data to an iOS or Android app via Bluetooth Smart. The app allows users to analyze sleep patterns, set alarms, and experiment with different sleeping patterns.

A number of high-profile wearable sensors purport to track sleep, but, as NeuroOn points out on its Kickstarter page, most only use an accelerometer. A major competitor in that space is Lark, which sports a smart alarm. Nike, Fitbit, and Jawbone have all added this kind of sleep tracking in their most recent offerings as well. Others, like the Basis Band, track heart rate or galvanic skin response during sleep.

When it comes to tracking brain waves, though, the field is much smaller. The most notable startup in that field was the now-defunct Zeo, which shut down earlier this year, but began with a similar approach toward maximizing sleep. Other EEG tracking headbands, like Melon, have mentioned an intention to move into sleep tracking, but aren't currently advertising that functionality.