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Delayed Sleep Phase

Meaning

Delayed Sleep Phase, or DSP, is a common circadian rhythm sleep-wake disorder characterized by a persistent and involuntary inability to fall asleep and wake up at conventional or socially desired times. Individuals with this disorder exhibit a significant delay in the timing of their major sleep episode, often preferring to sleep, for example, from 3:00 AM to 11:00 AM, rather than the typical 11:00 PM to 7:00 AM window. This internal misalignment between the body’s intrinsic clock and external social demands frequently results in chronic sleep deprivation and associated functional impairment. The core issue is a biologically fixed, later sleep schedule that conflicts with work or school obligations.