Relationship between reported and measured sleep times: the sleep heart health study (SHHS).

STUDY OBJECTIVE: Subjective and objective assessments of sleep may be discrepant due to sleep misperception and measurement effects, the latter of which may change the quality and quantity of a person's usual sleep. This study compared sleep times from polysomnography (PSG) with self-reports of habitual sleep and sleep estimated on the morning after a PSG in adults. DESIGN: Total sleep time and sleep onset latency obtained from unattended home PSGs were compared to sleep times obtained from a questionnaire completed before the PSG and a Morning Survey completed the morning after the PSG. PARTICIPANTS: A total of 2,113 subjects who were > or = 40 years of age were included in this analysis. MEASURES AND RESULTS: Subjects were 53% female, 75% Caucasian, and 38% obese. The mean habitual sleep time (HABTST), morning estimated sleep time (AMTST), and PSG total sleep times (PSGTST) were 422 min, 379 min, and 363 min, respectively. The mean habitual sleep onset latency, morning estimated sleep onset latency, and PSG sleep onset latency were 17.0 min, 21.8 min, and 16.9 min, respectively. Models adjusting for related demographic factors showed that HABTST and AMTST differ significantly from PSGTST by 61 and 18 minutes, respectively. Obese and higher educated people reported less sleep time than their counterparts. Similarly, small but significant differences were seen for sleep latency. CONCLUSIONS: In a community population, self-reported total sleep times and sleep latencies are overestimated even on the morning following overnight PSG.

Identification of sleep-disordered breathing in children: variation with event definition.

STUDY OBJECTIVES: To determine the effect of varying approaches to the measurement of the respiratory disturbance index (RDI) on identification of sleep disordered breathing (SDB) in children. DESIGN: Cross-sectional study of SDB in a well-characterized birth cohort (stratified for term and preterm birth) participating in longitudinal studies of cognition and behavior. SETTING: Community-based; overnight studies conducted in participant's homes. PARTICIPANTS: 433 children, ages 8-11 years, un-referred for clinical assessment of SDB. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Participants underwent unattended overnight in-home recording of respiratory inductance plethysmography, pulse oximetry, body position, and heart rate. The relationships among RDIs derived from various definitions of apnea and hypopneas and thresholds for frequency of events were assessed. Median RDI varied by more than 20-fold for definitions using the more liberal criteria for event definition (all respiratory events; i.e., central or obstructive events and hypopneas with no requirement for associated desaturation) to the most conservative definition (using obstructive apneas only or obstructive apnea and hypopneas requiring a 5% associated desaturation). Prevalence estimates for SDB based on RDIs that included central apneas were 40% to 140% higher than those that excluded central apneas. CONCLUSIONS: Different approaches for quantifying RDI contribute to substantial variability in identification and classification of SDB in children and will lead to discrepant estimates of its presence and severity.