Actigraphy is increasingly used to study sleep and circadian rhythms in individuals with intellectual and developmental disabilities, such as Rett syndrome. A study aimed to determine how recording duration affects the reliability of sleep and circadian rhythm measures in this population. Researchers collected two sets of 14-day recordings from 30 subjects, aged 2 to 36, with a focus on evaluating reliability based on different recording lengths.

Findings revealed that average sleep quality could be reliably assessed with recordings of 7 to 10 nights. However, the reliability of night-to-night variability in sleep timing was poor across all durations, while sleep duration variability showed adequate reliability with 5 to 7 days of recording. The reliability of circadian rhythm measures was found to be highly variable.

The study concludes that optimal recording durations differ depending on the specific metrics being assessed, but most sleep measures can be reliably recorded within the established timeframes.