Abstract
Purpose
The Pittsburgh Sleep Quality Index (PSQI) is a widely used measure for assessing sleep impairment. Although it was developed as a unidimensional instrument, there is much debate that it contains multidimensional latent constructs. We examined the dimensionality of the underlying factor structure of PSQI in Singapore, a rapidly industrialising Asian country with multi-ethnicities representing the Chinese, Malays and Indians.
Methods
The PSQI was administered through an interviewer-based questionnaire in two separate population-based cross-sectional surveys. An explanatory factor analysis (EFA) was first used to explore the underlying construct of the PSQI in both studies. Then, a confirmatory factor analysis (CFA) was conducted to evaluate an optimal factor model by comparing against other possible models identified in EFA.
Results
There are three correlated yet distinguishable factors that account for an individual’s sleep experience from the same best-fit model obtained in both studies: perceived sleep quality, daily disturbances and sleep efficiency. Our three-factor structure of PSQI is superior to the originally intended unidimensional model. Our model also shows the best-fit indices when compared to the previously reported single-factor, two-factor and three-factor (by Cole et al.) models in a multi-ethnic Asian population.
Conclusion
There is strong evidence that the PSQI contains a three-factor rather than a unidimensional structure in a multi-ethnic Asian population. Scoring the PSQI along their multidimensional perspectives may provide a more accurate understanding of the relationship between sleep impairment and health conditions rather than using a single global score.
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References
Ohayon MM (2008) Nocturnal awakenings and comorbid disorders in the American general population. J Psychiatr Res 43(1):48–54
Kim K, Uchiyama M, Okawa M, Liu X, Ogihara R (2000) An epidemiological study of insomnia among the Japanese general population. Sleep 23(1):41–47
Weyerer S, Dilling H (1991) Prevalence and treatment of insomnia in the community: results from the Upper Bavarian Field Study. Sleep 14(5):392–398, Epub 1991/10/01
Hohagen F, Rink K, Kappler C, Schramm E, Riemann D, Weyerer S et al (1993) Prevalence and treatment of insomnia in general practice. A longitudinal study. Eur Arch Psychiatry Clin Neurosci 242(6):329–336
Yeo BK, Perera IS, Kok LP, Tsoi WF (1996) Insomnia in the community. Singap Med J 37(3):282–284
Budhiraja R, Roth T, Hudgel DW, Budhiraja P, Drake CL (2011) Prevalence and polysomnographic correlates of insomnia comorbid with medical disorders. Sleep 34(7):859–867
Sarsour K, Morin CM, Foley K, Kalsekar A, Walsh JK (2010) Association of insomnia severity and comorbid medical and psychiatric disorders in a health plan-based sample: insomnia severity and comorbidities. Sleep Med 11(1):69–74
Maia Q, Grandner MA, Findley J, Gurubhagavatula I (2013) Short and long sleep duration and risk of drowsy driving and the role of subjective sleep insufficiency. Accid Anal Prev 59:618–22
Nakashima M, Morikawa Y, Sakurai M, Nakamura K, Miura K, Ishizaki M et al (2011) Association between long working hours and sleep problems in white-collar workers. J Sleep Res 20(1 Pt 1):110–116
Buysee DJ, Reynolds CF, Monk TH, Berman SR, Kupfer DJ (1989) The Pittsburgh Sleep Quality Index: a new instrument for psychiatry practice and research. Psychiatr Res 28:198–213
Jimenez-Genchi A, Monteverde-Maldonado E, Nenclares-Portocarrero A, Esquivel-Adame G, de la Vega-Pacheco A (2008) Reliability and factorial analysis of the Spanish version of the Pittsburg Sleep Quality Index among psychiatric patients. Gac Med Mex 144:491–496
Magee CA, Caputi P, Iverson DC, Huang X-F (2008) An investigation of the dimensionality of the Pittsburgh Sleep Quality Index in Australian adults. Sleep Biol Rhythms 6:222–227
Carpenter JS, Andrykowski MA (1998) Psychometric evaluation of the Pittsburgh Sleep Quality Index. J Psychosom Res 45:5–13
Cole JC, Motivala SJ, Buysse DJ, Oxman MN, Levin MJ, Irwin MR (2006) Validation of a 3-factor scoring model for the Pittsburgh Sleep Quality Index in older adults. Sleep 29:112–116
Aloba OO, Adewuya AO, Ola BA, Mapayi BM (2007) Validity of the Pittsburgh Sleep Quality Index (PSQI) among Nigerian university students. Sleep Med 8:266–270
Panayides et al (2013) Using Rasch measurement to create a quality of sleep scale for a non-clinical sample based on the Pittsburgh Sleep Quality Index (PSQI). Eur J Psychol 9(1):113–135
Pittsburgh Sleep Quality Index (PSQI), Sleep Medicine Institute, University of Pittsburgh. http://www.sleep.pitt.edu/content.asp?id=1484&subid=2316 Accessed 16 May 2014
Stevens JP (1992) Applied multivariate statistics for the social sciences, 2nd edn. Erlbaum, Hillsdale, NJ
Lê S, Josse J, Husson F (2008) FactoMineR: An R package for multivariate analysis. J Stat Softw 25(1):1–18
Bollen KA, Long JS (1993) Testing structural equation models. Sage, Newbury Park, CA
Bentler PM, Bonett DG (1980) Significance tests and goodness-of-fit in the analysis of covariance structures. Psychol Bull 88:588–606
Hu L, Bentler PM (1998) Fit indices in covariance structure modeling: sensitivity to underparameterized model misspecification. Psychol Methods 3:424–453
Schumacker RE, Lomax RG (2004) A beginner’s guide to structural equation modeling, 2nd edn. Lawrence Erlbaum Associates, Inc, Mahwa, NJ
Long JS (1983) Confirmatory factor analysis. Sage, Newbury Park, CA
Raftery AE (1993) Bayesian model selection in structural equation models. In: Bollen KA, Long JS (eds) Testing structural equation models. Sage, Newbury Park, CA, pp 163–180
R Core Development Team: R: A language and environment for statistical computing. http://www.R-project.org Accessed 16 May 2014
Cronbach LJ (1951) Coefficient Alpha and the internal structure of tests. Psychometrika 16:297–334
Cortina JM (1993) What is coefficient alpha? An examination of theory and applications. J Appl Psychol 78:98–104
Mariman A, Vogelaers D, Hanoulle I, Delesie L, Tobback E, Pevernagie D (2012) Validation of the three-factor model of the PSQI in a large sample of chronic fatigue syndrome (CFS) patients. J Psychosom Res 72(2):111–113. doi:10.1016/j.jpsychores.2011.11.004
Weng FC (2010) National Health Survey 2010, Singapore: Epidemiology & Disease Control Division, Ministry of Health. http://www.moh.gov.sg/content/moh_web/home/Publications/Reports/2011/national_health_survey2010.html. Accessed 16 May 2014
Acknowledgments
The Singapore Health (SH) survey is funded by the Ministry of Health, Singapore. The funder did not play a role in the design, conduct or analysis of the study as well as the drafting of this manuscript. The authors would also like to thank the group of Community Health Project (CHP) medical students of year 2012 from the National University of Singapore (NUS) for going out to conduct the surveys to collect data for the Queenstown study. We would also like to gratefully acknowledge Dr. Choi Hyungwon (NUS) for reading and providing editorial comments for our manuscript.
Ethical standards
Ethics review requirement was waived by the National University of Singapore (NUS) Institutional Review Board (IRB) as anonymous data was collected for the Queenstown study. For SH 2012, ethics was reviewed and approved by the NUS IRB prior to implementation. All subjects had given their informed consent prior to their inclusion in the study.
Conflict of interest
The authors declare that they have no competing interests.
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Koh, H.W.L., Lim, R.B.T., Chia, K.S. et al. The Pittsburgh Sleep Quality Index in a multi-ethnic Asian population contains a three-factor structure. Sleep Breath 19, 1147–1154 (2015). https://doi.org/10.1007/s11325-015-1130-1
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DOI: https://doi.org/10.1007/s11325-015-1130-1