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Objective components of individual differences in subjective sleep quality
1National Institute of Psychosocial Factors and Health and Department for Public Health Sciences, Karolinska Institute, Stockholm, Sweden.
Journal of Sleep Research
|March 11, 1998
Summary
This study explored the Karolinska Sleep Diary (KSD) and its relation to objective sleep measures. Deep sleep and sleep continuity are key components of perceived sleep quality.
Area of Science:
- Sleep Medicine
- Psychometrics
Background:
- Understanding the relationship between subjective sleep reports and objective polysomnography is crucial.
- The Karolinska Sleep Diary (KSD) is a tool used to assess subjective sleep experiences.
Purpose of the Study:
- To analyze the item structure of the KSD.
- To investigate the correlation between KSD responses and polysomnography-derived sleep variables.
- To examine these relationships in naturalistic conditions.
Main Methods:
- Cross-sectional study design.
- Polysomnography (PSG) was conducted on 37 participants before a workday.
- Participants completed the KSD after waking.
Main Results:
- Factor analysis of the KSD revealed two main factors: a sleep quality index (SQI) concerning sleep initiation/maintenance, and a factor related to waking difficulties and sleep sufficiency.
- Slow-wave sleep (SWS) and sleep efficiency were the strongest predictors of the SQI.
- Variables like total sleep time (TST) and stage 0 sleep also correlated with sleep quality.
Conclusions:
- Sleep quality appears to be primarily determined by the depth of sleep and sleep continuity.
- Findings align with previous laboratory-based sleep research.
- The KSD effectively captures subjective sleep experiences related to objective sleep parameters.