Comparing Two Common Self-Report Methods of Habitual Sleep Duration in Epidemiological Surveys
Prof. Maria Korman
Prof. Maria Korman began her scientific journey from studying neurobiology, sleep and memory at the Weizmann Institute of Science (Israel) and Montreal University (Canada). Currently, she is the head of the TO-Be Lab (Temporal Organization of Behavior laboratory) that investigates human sleep-wake, eating-fasting, and cognitive daily cycles and the temporal organization of human memory consolidation at Ariel University, Israel.
Towards a Better Assessment of Self-Reported Sleep Duration in Surveys
Many epidemiological studies examining the relationship between subjective measures of habitual sleep duration (HSD) and health outcomes rely on a single self-report question or a two-question assessment of sleep interval. Evaluating differences between self-report methods used to measure HSD in surveys is crucial for understanding biases and influencing factors leading to poor agreement. This study, led by Prof. Korman (Israel) and Dr. Reis (Portugal), aimed to assess the bias and agreement limits between two commonly used short HSD self-report methods, considering sleep quality and social jetlag as potential predictors of bias.
Two methods were compared: 1) a single question about habitual sleep duration (self-reported HSD); and 2) estimated HSD (estimated HSD) from reported sleep times on workdays and free days from the Munich Chronotype Questionnaire (MCTQ). Sleep quality was reported using a Likert scale.
We analyzed data from 10,268 participants in the International COVID Sleep Study-II (ICOSS-II). Self-reported HSD was on average 42.41±67.42 minutes lower than estimated HSD, with an agreement range within ±133 minutes. The bias and agreement range between methods increased with poorer sleep quality and were sensitive to whether the estimated HSD was reported for work or work-free days. Estimated HSD on work days showed smaller bias and better agreement with self-reported HSD compared to estimated HSD for free days. Sleep duration irregularity between work and work-free days was -43.35±78.26 minutes on average. Altogether, the two methods showed very poor agreement and a significant systematic bias, both worsening with poorer sleep quality. Estimated HSD considered sleep intervals without adjusting for sleep quality such as wakefulness after sleep onset but accounted for sleep irregularity and sleeping in on free days, while self-reported HSD reflected respondents’ interpretation of their sleep, focusing on their sleep on workdays.
Selecting individual questions in epidemiological studies becomes crucial when comprehensive methods are not feasible. A single question regarding sleep duration represents how the respondents interpret their sleep and is highly sensitive to subjective sleep issues, however, it may lack the ability to detect the highly probable occurrence of sleep rebound on free days (i.e. catching up on sleep at the weekends). The two-question method enables the estimation of additional valuable sleep metrics like sleep duration irregularity, social jetlag and mid-point of sleep, but does not take into account wakefulness after sleep onset. Separate HSD assessments for workdays and free days using either approach, combined with including an sleep quality related question in surveys may help bidirectionally adjust the possible bias and enhance the accuracy of sleep-health studies and enhance the design of epidemiological studies.
Article based on Korman et al. (2024). Estimation bias and agreement limits between two common self-report methods of habitual sleep duration in epidemiological surveys. Sci Rep.
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