Sleep Med Psychophysiol.  2015 Jun;22(1):11-19. 10.14401/KASMED.2015.22.1.11.

The Effect of Insomnia Severity on Daytime Sleepiness in Obstructive Sleep Apnea Syndrome

  • 1Department of Neuropsychiatry, The Armed Forces Chung-pyung Hospital, Gapyeong, Korea.
  • 2Department of Neuropsychiatry, Konkuk University Hospital, Seoul, Korea.
  • 3Advanced Scientific Research Group in Asia Pacific International School, Seoul, Korea.


Whether daytime sleepiness is proportional to the severity of sleep apnea in obstructive sleep apnea syndrome (OSAS) is controversial. In this study we investigated how insomnia severity affects the association between daytime sleepiness and sleep apnea severity in OSAS.
The present study included 235 male subjects who were diagnosed with OSAS based on clinical history and nocturnal polysomnography. Pearson's correlation analysis was conducted among sleep and mood-related self-reported data, polysomnographic data and demographic data of all subjects. Based on Pittsburgh Sleep Quality Index (PSQI), the subjects were divided into 2 groups; group A (n = 75; PSQI < or =5) and group B (n = 160; PSQI > 5). Partial correlation analysis was performed between the Epworth Sleepiness Scale (ESS) and other data in both groups. Multiple linear regression analysis was conducted to investigate the factors which affected the ESS in group A.
Pearson's correlation analysis showed weak or non-existent correlations between ESS and apnea severity data such as apnea-hypopnea index (AHI) (r = 0.148, p = 0.023), apnea index (AI) (r = 0.137, p = 0.036), hypopnea index (HI) (r = 0.058, p = 0.377), oxygen desaturation index (ODI) (r = 0.149, p = 0.022) and arousal total index (ATI) (r = 0.129, p = 0.048). Positive correlations between ESS and apnea severity data such as AHI (r(p) = 0.313, p = 0.008), AI (r(p) = 0.339, p = 0.004), ODI (r(p) = 0.289, p = 0.015) and ATI (r(p) = 0.256, p = 0.031) were observed only in group A. Multiple regression analysis showed that AI (t = 2.996, p = 0.004) and BAI (t = 2.721, p = 0.008) were associated with ESS in group A.
The correlation between daytime sleepiness and sleep apnea severity was shown only in group A. This result suggests that associations between daytime sleepiness in OSAS and sleep apnea severity will become prominent when controlling for insomnia-related variables.


Obstructive sleep apnea syndrome; Daytime sleepiness; Epworth sleepiness scale; Pittsburgh sleep quality index
Full Text Links
  • SMP
export Copy
  • Twitter
  • Facebook
Similar articles
Copyright © 2021 by Korean Association of Medical Journal Editors. All rights reserved.     E-mail: