Self-reported sleep duration and timing: A methodological review of event definitions, context, and timeframe of related questions

Abstract

Study objectives

Clinical and population health recommendations are derived from studies that include self-report. Differences in question wording and response scales may significantly affect responses. We conducted a methodological review assessing variation in event definition(s), context (i.e., work- versus free-day), and timeframe (e.g., “in the past 4 weeks”) of sleep timing/duration questions.

Methods

We queried databases of sleep, medicine, epidemiology, and psychology studies for survey-based research and/or publications with sleep duration/timing questions. The text of these questions was thematically analyzed.

Results

We identified 53 surveys with sample sizes ranging from 93 to 1,185,106. For sleep duration questions, participants reported nocturnal sleep (24 of 44 questions), sleep in the past 24-hours (14/44), their major sleep episode (3/44), or answered unaided (3/44). For bedtime questions, participants reported time into bed (19/47), first attempt to sleep (16/40), or fall-asleep time (12/47). For wake-time questions, participants reported wake-up time (30/43), the time they “get up” (7/43), or their out-of-bed time (6/43). Context guidance appeared in 18/44 major sleep duration, 35/47 bedtime, and 34/43 wake-time questions. Timeframe was provided in 8/44 major sleep episode duration, 16/47 bedtime, and 10/43 wake-time questions. One question queried the method of awakening (e.g., by alarm clock), 18 questions assessed sleep latency, and 12 measured napping.

Conclusion

There is variability in the event definition(s), context, and timeframe of questions relating to sleep. This work informs efforts at data harmonization for meta-analyses, provides options for question wording, and identifies potential questions for future surveys.