1. A system for monitoring movement of a person's eye, comprising: a device configured to be worn on a person's head; an array of one or more emitters on the device for directing light towards an eye of the person when the device is worn , the array of emitters configured for projecting a reference frame towards the eye ; and a camera oriented towards the eye for monitoring movement of the eye relative to the reference frame mounted on the device ; and one or more sensors on the device for detecting light from the array of one or more emitters that is reflected off of the eye or its eyelid, the one or more sensors producing an output signal indicating when the eye is open or closed.