Abstract
(1) Background: The Pittsburgh Sleep Quality Index (PSQI) is a useful tool for the assessment of subjective sleep quality in non-clinical and clinical settings. This study aimed to determine sleep quality in a general Malaysian adult population using a validated Malay version of the Pittsburgh sleep quality index (PSQI-M); (2) Methods: The original PSQI was translated into Malay following forward and backward translation guidelines. The final Malay version was administered to a sample of healthy working adults (n = 106; mean age: 35.3 ± 7.6 years) without history of sleep disorders. Reliability and agreement were assessed using Cronbach’s alpha, intra-class correlations coefficient (ICC), standard error of measurement (SEM), and Bland–Altman plot. Convergent validity of PSQI-M was examined with the Malay version of Epworth sleepiness scale (ESS-M) using Pearson’s correlation coefficient; (3) Results: Overall mean PSQI global score was 5.25 ± 1.85. About 45% of the sample had PSQI global score >5, indicating poor sleep quality. Total sleep duration per night was 5.95 ± 1.05 h, below the recommended amount. Sleep quality seems to be affected by age but not gender. Internal consistency as measured by Cronbach’s alpha in the whole sample was 0.74, with test–retest reliability (ICC) of 0.58 and SEM of 1.34. The PSQI test–retest scores indicated that most of the respondents (90%) lay within the 95% limits of agreement. The PSQI-M also showed significant correlation with ESS-M scores (r = 0.37, p < 0.01); (4) Conclusion: The PSQI-M showed acceptable reliability and is valid to be used in a general Malaysian adult population. Findings also indicate that a majority of the adults in our sample were experiencing inadequate sleep, thus further research is needed to identify the factors associated with poor sleep quality.
Highlights
Good sleep quality is one of the most important factors contributing to physical functioning, psychological well-being, and quality of life
There was no improvement in internal consistency for Pittsburgh Sleep Quality Index (PSQI)-M when any of the items were deleted
The intra-class correlations coefficient (ICC) for Pittsburgh Sleep Quality Index Malay Version (PSQI-M) subcomponents ranged from 0.40 for daily dysfunction to 0.62
Summary
Good sleep quality is one of the most important factors contributing to physical functioning, psychological well-being, and quality of life. Sleep quality is often used to refer to a collection of sleep measures such as total sleep duration, sleep onset latency, sleep efficiency, wakefulness after sleep onset, and daytime sleepiness [1,2]. Sleep quality can be distinguished between subjective and objective sleep quality. Sufficient total sleep time, reduced wake after sleep onset, and alertness during daytime are often viewed as indicators of good subjective sleep quality [3]. In addition to the measures aforementioned, good sleep quality can be objectively inferred as having proper amount and relative distribution of each of the sleep stages i.e., stage 1, stage 2, slow wave sleep, and rapid eye movement (REM), measured using polysomnography [2].
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