Moderately strong intraclass correlations between actigraphic and polysomnographic total sleep time and sleep efficiency in older adults with sleep disturbance.

Objective: To evaluate the reliability of the GeneActiv actigraphy device in measuring sleep parameters and compare its performance with polysomnography (PSG) in older adults with self-reported sleep disturbances.

Methods: This sub-study was part of a pilot double-blinded randomized controlled crossover trial (CleverLights Study, ANZCTR ID 12619000138189). Participants (n = 12, mean age 67.7 years) underwent two nights of sleep studies with simultaneous GeneActiv actigraphy and PSG, separated by a 2-week interval. Sleep parameters including time in bed (TIB), total sleep time (TST), wake after sleep onset (WASO), sleep onset latency (SOL), sleep efficiency (SE), and number of awakenings were assessed. Intraclass Correlation Coefficients (ICCs) and Bland-Altman plots were used to determine reliability and agreement between methods.

Results: GeneActiv actigraphy demonstrated strong correlations with PSG for TST (ICC = 0.79, p = 0.001) and SE (ICC = 0.85, p < 0.001), but tended to overestimate these parameters. Actigraphy also significantly underestimated the number of awakenings (ICC = 0.45, p = 0.021). Correlations with observed TIB (ICC = 0.30, p = 0.433), WASO (ICC = 0.33, p = 0.386), and SOL (ICC = 0.32, p = 0.056) were non-significant. Bland-Altman plots revealed proportional bias, especially in SOL and the number of awakenings.

Conclusion: Compared to PSG, the GeneActiv actigraphy device provides reliable measurements for total sleep time and sleep efficiency, but agreement was weaker for wake after sleep onset, sleep onset latency, and the number of awakenings. The device showed consistent performance across multiple nights, suggesting good reproducibility. However, it systematically overestimated total sleep time and underestimates wake-related parameters, hence it may not fully replace PSG for detailed sleep assessments.