Psychometric evaluation of the Epworth sleepiness scale in an obstetric population

Sleep Med. 2013 Jan;14(1):116-21. doi: 10.1016/j.sleep.2012.10.007. Epub 2012 Dec 4.


Background: The Epworth Sleepiness Scale (ESS) was initially developed to measure daytime sleep propensity in patients affected by a variety of sleep disorders. Obstetrical research has measured sleepiness in pregnant women with the ESS, although psychometric analyses and dimensionality evaluations have never been conducted with this population.

Objective: The objective was to perform a psychometric evaluation of the ESS in an obstetric population. The design was a secondary data analysis of the subjects enrolled in the Prenatal Exposures and Preeclampsia Prevention III (PEPP) study. The setting for the subjects who received prenatal care was at Magee-Women's Hospital UPMC in Pittsburgh, Pennsylvania and included 337 pregnant women in their first trimester that completed the ESS.

Methods: Principal components analysis and confirmatory factor analysis were performed using SPSS and M-Plus. Additionally, reliability was assessed and construct validity was measured using the Life Orientation Test (LOT). Lastly, a relationship between daytime sleepiness and snoring was investigated using item 5e from the Pittsburgh Sleep Quality Index (PSQI).

Results: PCA with varimax rotation yielded two factors that explained approximately 50% of the variance and CFA results verified this two-factor solution. An overall Cronbach's alpha (0.751) revealed moderate reliability (Factor 1α=.754; Factor 2α=.524). Both convergent and discriminant validity were established.

Conclusion: The ESS is appropriate for use in an obstetric population to measure daytime sleepiness. Future work should include additional evaluations of the ESS in a diverse group of pregnant women.

Publication types

  • Evaluation Study

MeSH terms

  • Factor Analysis, Statistical
  • Female
  • Humans
  • Pregnancy
  • Pregnancy Complications / diagnosis*
  • Pregnancy Complications / physiopathology
  • Pregnancy Complications / psychology
  • Pregnancy Trimester, First / physiology
  • Pregnancy Trimester, First / psychology
  • Principal Component Analysis
  • Psychological Tests
  • Psychometrics
  • Reproducibility of Results
  • Sleep Wake Disorders / diagnosis*
  • Sleep Wake Disorders / physiopathology
  • Sleep Wake Disorders / psychology
  • Surveys and Questionnaires
  • Wakefulness / physiology
  • Young Adult