Reliability of Actigraphy for the Assessment of Sleep and Circadian Rhythms in Rett and Related Syndromes

Purpose Actigraphy is being increasingly used to assess sleep and circadian rhythms among populations with intellectual and developmental disabilities and genetic syndromes, including Rett syndrome and related disorders, but the reliability of these measures in these populations is unclear. The primary purpose of the current study was to evaluate the impact of recording duration on the reliability of various measures of sleep and circadian rhythm in Rett and related syndromes. Method Two 14‐day recordings were collected between 4 and 12 weeks apart in a sample of 30 individuals (aged 2–36 years; 97% female). Reliability was estimated by calculating statistics based on 3, 5, 7, 10 or 13–14 nights of recording. Results Most measures of average sleep quality could be reliably estimated with 7–10 nights. Measures of night‐to‐night variability in sleep timing showed poor reliability at all recording durations, whereas night‐to‐night variability in sleep duration showed adequate reliability at 5–7 days of recording. The reliability of measures of circadian rhythm was highly variable. Conclusions The results suggest that the optimal recording durations for actigraphy in this population vary based on the specific metrics of interest, but most can be measured reliably.