While skeptical psychological researchers continue to label claims of revelation and transcendence through altered states of consciousness as delusional and self-deceptive, others call for a serious examination of various states of consciousness and ask for more research to learn the particular significance of each state on the totality of the human entity. Many parapsychologists firmly believe that continued research into altered states of consciousness may well reveal that humankind's most important discoveries, its highest peaks of ecstasy, and its greatest moments of inspiration occur in reverie, in dreams, and in states of consciousness presently ignored by the professional world and the general public.
In a related perceptual phenomenon, flash suppression , the percept associated with an image projected into one eye is suppressed by flashing another image into the other eye while the original image remains. Its methodological advantage over binocular rivalry is that the timing of the perceptual transition is determined by an external trigger rather than by an internal event. The majority of cells in the inferior temporal cortex and the superior temporal sulcus of monkeys trained to report their percept during flash suppression follow the animal's percept: when the cell's preferred stimulus is perceived, the cell responds. If the picture is still present on the retina but is perceptually suppressed, the cell falls silent, even though primary visual cortex neurons fire.   Single-neuron recordings in the medial temporal lobe of epilepsy patients during flash suppression likewise demonstrate abolishment of response when the preferred stimulus is present but perceptually masked. 
In FIG. 2, a read-only memory (ROM) 10 stores frequency sequences corresponding to different parts of a human sleep cycle. The stored frequency sequences may be in accordance with a predetermined algorithm, or alternatively may provide a less complex entrainment environment, such as simple averaging. A digital signal processor (DSP) 20 selects different ones of these sequences based on the current time and the time to which an alarm is set. The time is displayed on display 30, and is set using time set 40. The alarm is set to a desired wake-up time using alarm set 50.