Skip to main content
SpringerLink
Log in

Can we get more from the Epworth Sleepiness Scale (ESS) than just a single score?

A confirmatory factor analysis of the ESS

  • Original Article
  • Published:
Sleep and Breathing Aims and scope Submit manuscript

Abstract

Purpose

The Epworth Sleepiness Scale (ESS) is a widely used tool for measuring sleepiness. In addition to providing a single measure of sleepiness (a one-factor structure), the ESS also has the capacity to provide additional information about specific factors that facilitate sleep onset, including a person’s posture, activity and environment. These features of sleepiness are referred to as somnificity. This study evaluates and compares the fit of a one-factor structure (sleepiness) and three-factor structure (reflecting low, medium and high levels of somnificity) for the ESS.

Methods

All participants (a community sample N = 356 and a clinical sample N = 679) were administered the ESS. Confirmatory factor analysis was used to evaluate and compare the fit of one- and three-factor models of the ESS.

Results

In both samples, a three-factor structure (community sample adjusted X 2 = 2.95, root mean square error of approximation (RMSEA) = 0.07, Comparative Fit Index (CFI) = 0.95; clinical sample adjusted X 2 = 3.98, RMSEA = 0.07, CFI = 0.98) provided a level of model fit that was at least as good as the one-factor structure (community sample adjusted X 2 = 5.01, RMSEA = 0.11, CFI = 0.87; clinical sample adjusted X 2 = 8.87, RMSEA = 0.11, CFI = 0.92).

Conclusions

In addition to a single measure of sleepiness, the ESS can provide subscale scores which relate to three underlying levels of somnificity. These findings suggest that the ESS can be used to measure an individual’s overall sleep propensity as well as more specific measures of sleep propensity in low, moderate and high levels of situational somnificity.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2

Similar content being viewed by others

References

  1. Sauter C, Senbaum SA, Popvic R, Bauer H, Lamm C, Klosch G, Zeitlhofer J (2010) Excessive daytime sleepiness in patients suffering from different levels of obstructive sleep apnoea syndrome. J Sleep Res 9:293–301

    Article  Google Scholar 

  2. Tsai JCG (2010) Neurological and neurobehavioural sequelae of obstructive sleep apnea. Neurorehabilitation 26:85–94

    PubMed  Google Scholar 

  3. Webb W (1995) The cost of sleep-related accidents: a reanalysis. Sleep 18:276–280

    PubMed  CAS  Google Scholar 

  4. Lyznicki JM, Doege TC, Davis RM, Williams MA (1998) Sleepiness, driving and motor vehicle crashes. J Am Med Assoc 279:1908–1913

    Article  CAS  Google Scholar 

  5. Takegami M, Morita S, Chin K, Akashiba T, Kimura H, Suzukamo Y, Fukuhara S (2011) Impact of excessive daytime sleepiness on health-related quality of life in patients with obstructive sleep apnea syndrome. Qual Life Res 13:1555

    Google Scholar 

  6. Johns MW (1991) A new method for measuring daytime sleepiness: the Epworth sleepiness scale. Sleep 14:540–545

    PubMed  CAS  Google Scholar 

  7. Johns MW (2002) Sleep propensity varies with behaviour and the situation in which it is measured: the concept of somnificity. J of Sleep Res 11:61–67

    Article  Google Scholar 

  8. Izci B, Ardic S, Firat H, Sahin A, Altinors M, Karacan I (2008) Reliability and validity studies of the Turkish version of the Epworth Sleepiness Scale. Sleep Breath 12:161–168

    Article  PubMed  Google Scholar 

  9. Chen N-H, Johns MW, Li H-Y, Chu C-C, Liang S-C, Shu Y-H, Chuang M-L, Wang P-C (2002) Validation of a Chinese version of the Epworth sleepiness scale. Qual Life Res 11:817–821

    Article  PubMed  Google Scholar 

  10. Bloch KE, Schoch OD, Zhang JN, Russi EW (1999) German version of the Epworth Sleepiness Scale. Respiration 66:440–447

    Article  PubMed  CAS  Google Scholar 

  11. Shahid A, Shen J, Shapiro C (2010) Measurements of sleepiness and fatigue. J Psychom Res 69:81–89

    Article  Google Scholar 

  12. Johns MW (1994) Sleepiness in different situations measured by the Epworth Sleepiness Scale. Sleep 17:703–710

    PubMed  CAS  Google Scholar 

  13. MacCallum RC, Austin JT (2010) Applications of structural equation modelling in psychology research. Annu Rev Psychol 51:201–226

    Article  Google Scholar 

  14. Iaccobucci D (2010) Structural equation modelling: fit indices, sample size, and advanced topics. J Consum Psychol 20:90–98

    Article  Google Scholar 

  15. Byrne BM (2010) Structural equation modelling with AMOS: basic concepts, application and programming, 2nd edn. Taylor Francis Group, New York

    Google Scholar 

  16. Floyd FJ, Widaman KF (1995) Factor analysis in the development and refinement of clinical assessment instruments. Psychol Assess 7:286–299

    Article  Google Scholar 

  17. Heaton K, Anderson D (2007) A psychometric evaluation of the Epworth Sleepiness Scale. J Nurs Meas 15:177–188

    Article  PubMed  Google Scholar 

  18. Johns MW (1992) Reliability and factor analysis of the Epworth Sleepiness Scale. Sleep 15:376–381

    PubMed  CAS  Google Scholar 

  19. Kingshott RN, Engleman HM, Deary IJ, Douglas NJ (1998) Does arousal frequency predict daytime function? Eur Resp J 12:1264–1270

    Article  CAS  Google Scholar 

  20. Smith SS, Oei TPS, Douglas JA, Brown I, Jorgensen G, Andrews J (2008) Confirmatory factor analysis of the Epworth Sleepiness Scale (ESS) in patients with obstructive sleep apnoea. J Sleep Med 9:739–744

    Article  Google Scholar 

  21. Johns M, Hocking B (1997) Daytime sleepiness and sleep habits of Australian workers. Sleep 10:844–849

    Google Scholar 

  22. SPSS Inc (2009) SPSS for Windows, Rel. 18.0.0. SPSS Inc, Chicago

    Google Scholar 

  23. Arbuckle JL (2009) Amos 18.0, Version 2.0. SPSS Inc, Chicago

    Google Scholar 

  24. Hu L, Bentler PM (1999) Cutoff criteria for fit indexes in covariance structure analysis: conventional criteria versus new alternatives. Struct Equ Model 6:1–55

    Article  Google Scholar 

  25. Kline RB (2004) Beyond significance testing. American Psychological Association, Washington, DC

    Book  Google Scholar 

  26. Perlis ML, Jungquist C, Smith M, Posner D (2005) Cognitive behavioural treatment of insomnia: a session-by-session guide. Springer, New York

    Google Scholar 

  27. Fabrigar LR, Wegener DT, MacCallum RC, Strahan EJ (1999) Evaluating the use of exploratory factor analysis in psychological research. Psychol Methods 4:272–299

    Article  Google Scholar 

  28. Green SB, Lissitz RW, Mulaik SA (1977) Limitations of coefficient alpha as an index of test unidimensionality. Educ Psychol Meas 37:827–838

    Article  Google Scholar 

Download references

Acknowledgments

This study would not have been possible without the essential and gracious support of many individuals: Professor David Hillman, Christine Maguire and the sleep technologists of Sir Charles Gairdner Hospital, as well as the students of the University of Western Australia, Tamara De Regt, Alisa Holt, Anna Wallace, Stephanie Whitworth, Alix Mellor, Andrew Nienaber, Jacinta Hatton and Shraddha Kashyup.

Author information

Authors and Affiliations

  1. School of Psychology, University of Western Australia, Perth, Australia

    Michelle Olaithe, Jemma Clarke & Romola S. Bucks

  2. Rural Clinical School, University of Tasmania, Tasmania, Australia

    Timothy C. Skinner

  3. Centre for Sleep Science, School of Anatomy and Human Biology, The University of Western Australia, Perth, WA, Australia

    Peter Eastwood

  4. Western Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Perth, WA, Australia

    Peter Eastwood

  5. M304, School of Psychology, University of Western Australia, 35 Stirling Hwy Crawley, Perth, WA, 6009, Australia

    Michelle Olaithe

Authors
  1. Michelle Olaithe
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Timothy C. Skinner
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Jemma Clarke
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Peter Eastwood
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Romola S. Bucks
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Michelle Olaithe.

Additional information

The work was conducted at the School of Psychology, University of Western Australia, Perth, Australia and Western Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia.

Electronic supplementary material

Below is the link to the electronic supplementary material.

ESM 1

DOC 42 kb

Rights and permissions

Reprints and permissions

About this article

Cite this article

Olaithe, M., Skinner, T.C., Clarke, J. et al. Can we get more from the Epworth Sleepiness Scale (ESS) than just a single score?. Sleep Breath 17, 763–769 (2013). https://doi.org/10.1007/s11325-012-0763-6

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s11325-012-0763-6

Keywords

Search

Navigation