Photosensitivity during the hypersomnic phase in a patient with Kleine-Levin syndrome.

The case of an adolescent with Kleine-Levin syndrome is presented who exhibited a consistent and predictable photoparoxysmal self-limited response to intermittent photic stimulation during all relapses of his hypersomnic phase. A possible cause of this association that has not been previously reported is speculated based on observations concerning the two disorders.