The Development, Inter-rater Agreement and Performance of a Hierarchical Procedure for Setting the Rest-interval in Actigraphy Data

Background: This is a two-part study. The aim of study 1 was to identify common practices for setting rest intervals in actigraphy research and investigate whether standardized guidelines for setting the rest interval exist, as a base to develop a new procedure for defining rest intervals in actigraphy. The aim of study 2 was to empirically test this procedure (The Rest Interval Setting, RISE Procedure). The RISE procedure was applied to a dataset of 537 nights from the sleep study SLEEPIC.

Participants: Participants (N = 55) were aged 19-33 (M = 22.7, SD = 3.0).

Methods: Study 1: Structured overview of the methods used to correct actigraphy data. Study 2: Three scorers independently applied the RISE procedure to the dataset.

Results: Study 1 demonstrated that methods and reporting practices are inconsistent and that there is a need for a standardized procedure for setting the rest interval. The results in study 2 revealed that using the new procedure for setting rest intervals provided high agreement between scorers for both rest onsets (α= 0.975) and offsets (α= 0.998). Applying the procedure to the dataset resulted in a shortening of the rest interval by 36 min and 19 s on average. There were significant changes (p < 0.001) in all sleep estimate outcomes after applying the RISE procedure.

Conclusion: Methods for processing and reporting actigraphy data are highly inconsistent across studies. Here we present empirical support for a new standardized procedure for setting the rest interval, which is likely to improve transparency and reproducibility in achigraphy research.