DSPd

Delayed Sleep Phase Disorder (DSPD) is a circadian rhythm sleep disorder characterized by a stable misalignment between a person’s internal clock and conventional societal schedules, leading to markedly delayed sleep onset and wake times. Individuals with DSPD typically cannot fall asleep at conventional evening hours and struggle to wake up for morning obligations, resulting in chronic sleep deprivation, daytime sleepiness, mood disturbances, and impairment in school or work performance.

DSPD is thought to involve a delayed timing of the circadian clock, reduced sensitivity to morning zeitgebers such as light, and/or behavioral factors that reinforce late sleeping. Onset often occurs in adolescence or young adulthood and can persist for years. The condition is distinct from common insomnia because total sleep time may be preserved when a person follows a later schedule, though daytime impairment arises from misalignment with social demands.

Diagnosis is based on clinical history, sleep logs or actigraphy showing a consistent delay of sleep timing relative to desired schedule for at least several weeks, with preserved total sleep time and no other medical or psychiatric condition accounting for the pattern. Polysomnography is not routinely required. Differential diagnosis includes other circadian rhythm disorders and primary insomnia, as well as mood or anxiety disorders that can influence sleep patterns.

Management focuses on gradually advancing sleep timing and maintaining a consistent schedule. Treatments include timed bright light exposure in the morning to advance the circadian phase, melatonin taken a few hours before the desired bedtime, and strict sleep–wake hygiene. Chronotherapy and CBT-I adaptations may be used. The condition is more common in adolescents and young adults and can be persistent but is usually manageable with medical follow-up and lifestyle adjustments.