This case study describes a 14-year-old male suffering from significant academic and personal difficulties, who has been diagnosed with depression, schizotypal personality disorder, and learning disabilities. Because of excessive sleepiness, assessment for a potential sleep disorder was performed. An overnight polysomnographic study revealed no primary sleep disorders. Wrist actigraphy revealed a non-24-hour sleep-wake pattern. Delay in temperature rhythm and dissociation with melatonin rhythms were also noted. Treatment with oral melatonin restored normal sleep-wake schedule. In a follow-up psychiatric evaluation, none of the above diagnoses were present. Greater awareness of sleep disorders may prevent psychiatric misdiagnosis of treatable sleep-wake schedule disorders.