Sleep latency and duration estimates among sleep disorder patients: Variability as a function of sleep disorder diagnosis, sleep history, and psychological characteristics

Study Objectives: Insomnia patients often report greater sleep disturbance than found via polysomnography; yet the specific patient factors related to such sleep time misperceptions are poorly understood. We sought to charact erize the extent to which a diverse group of patients complaining of insomn ia (n = 104) misperceive overnight total sleep time and sleep latency, and to identify patient factors associated with these variations. Design: Cross-sectional. Setting: University based sleep disorders center. Patients: Sleep disorder groups consisted of patients with psychophysiologi cal insomnia (n=19), sleep state misperception (n=8), insomnia with depress ive disorder (n=11), insomnia secondary to Axis I psychiatric disorder othe r than depression (n=21), periodic limb movement disorder (n=24), and obstr uctive sleep apnea (n=21), Measurement and Results: Patients completed a sleep history questionnaire a nd the MMPI, underwent overnight diagnostic polysomnographic assessment, an d then estimated their total sleep time and sleep latency the subsequent mo rning. On average, patients overestimated sleep latency, but were equally l ikely to underestimate vs. overestimate total sleep time. Sleep time misper ception was associated with longer periods of wakefulness following sleep o nset, greater self-perceived sleep impairment, as well as several psycholog ical dimensions. Conclusions: Patient factors, including sleep quality, perceptions of habit ual sleep time, and current psychopathology, potentially influence sleep ti me estimation. Whereas psychological factors may lead to exaggeration of sl eep disturbance among some patients, sleep quality itself may also influenc e the congruence between subjective and objective indices of sleep.