Actigraphy for the Assessment of Sleep Measures in Parkinson's Disease

OBJECTIVES: To assess the usefulness of actigraphy for assessment of nighttime sleep measures in patients with Parkinson's disease (PD). DESIGN: Participants underwent overnight sleep assessment simultaneously by polysomnography (PSG) and actigraphy. SETTING: Overnight sleep study in academic sleep research laboratory. PARTICIPANTS: Sixty-one patients (mean age 67.74 ± 8.88 y) with mild to moderate PD. MEASUREMENTS: Sleep measures including total sleep time (TST), sleep efficiency (SE), wake after sleep onset (WASO), and sleep onset latency (SOL) were calculated independently from data derived from PSG and from actigraphy. Different actigraphy scoring settings were compared. RESULTS: No single tested actigraphy scoring setting was optimal for all sleep measures. A customized setting of an activity threshold of 10, with five consecutive immobile minutes for sleep onset, yielded the combination of mean TST, SE, and WASO values that best approximated mean values determined by PSG with differences of 6.05 ± 85.67 min for TST, 1.1 ± 0.641% for SE, and 4.35 ± 59.56 min for WASO. There were significant but moderate correlations between actigraphy and PSG measurements (rs = 0.496, P < 0.001 for TST, rs = 0.384, P = 0.002 for SE, and rs = 0.400, P = 0.001 for WASO) using these settings. Greater disease stage was associated with greater differences between TST (R(2) = 0.099, beta = 0.315, P = 0.018), SE (R(2) = 0.107, beta = 0.327, P = 0.014), and WASO (R(2) = 0.094, beta = 0.307, P = 0.021) values derived by actigraphy and PSG explaining some of the variability. Using a setting of 10 immobile min for sleep onset yielded a mean SOL that was within 1 min of that estimated by PSG. However SOL values determined by actigraphy and PSG were not significantly correlated at any tested setting. CONCLUSIONS: Our results suggest that actigraphy may be useful for measurement of mean TST, SE, and WASO values in groups of patients with mild to moderate Parkinson's disease. However, there is a significant degree of variability in accuracy among individual patients. The importance of determining optimal scoring parameters for each population studied is underscored.