Development and evaluation of a measure to assess restorative sleep

Abstract

Background: There are validated measures assessing insomnia and disturbed sleep, but few psychometrically sound instruments to assess perceptions of the restorative or inadequate properties of sleep are available.

Study objectives: To develop and evaluate a new instrument, the Restorative Sleep Questionnaire (RSQ).

Design and setting: Focus groups were conducted using participants with and without nonrestorative sleep complaints. Questions were designed to elicit the feelings and experiences people have about their sleep and their view of daytime consequences of sleep. Expert panels confirmed the importance of nonrestorative sleep (NRS) as a frequently encountered problem either with or without other sleep complaints. The resulting RSQ was administered in three studies: (1) a telephone interview with healthy controls and individuals with sleep problems; (2) a randomized clinical trial of patients with primary insomnia assessed by polysomnography (PSG); (3) a PSG study of subjects with NRS complaints.

Measurement and results: Across all studies, the new measures were shown to be significantly correlated with health-related quality of life (HRQL) domains hypothesized to be related to NRS. The RSQ had good psychometric properties (α > 0.90; rtest-retest > 0.80), and factor analysis confirmed the unidimensionality of the measure. The RSQ was able to distinguish between healthy controls, patients with primary insomnia, and insomnia patients with isolated NRS complaints but without PSG defined sleep onset, duration, or maintenance problems. Normal sleepers reported sleep that was about a standard deviation more restorative than that of those with NRS on the RSQ.

Conclusions: The results of the study provide support for the reliability and validity of the RSQ as a measure of NRS in subjects with and without self-reported or PSG confirmed sleep initiation and maintenance difficulties.

Clinicaltrialsgov identifiers: NCT00655369; NCT00705601.

Keywords: NRS; next day consequences; patient reported outcome; sleep perception; sleep quality.