title: The association between daytime napping and cognitive functioning in chronic fatigue syndrome.
abstract: OBJECTIVE
  The precise relationship between sleep and physical and mental functioning in chronic fatigue syndrome (CFS) has not been examined directly, nor has the impact of daytime napping. This study aimed to examine self-reported sleep in patients with CFS and explore whether sleep quality and daytime napping, specific patient characteristics (gender, illness length) and levels of anxiety and depression, predicted daytime fatigue severity, levels of daytime sleepiness and cognitive functioning, all key dimensions of the illness experience.
  
  
  METHODS
  118 adults meeting the 1994 CDC case criteria for CFS completed a standardised sleep diary over 14 days. Momentary functional assessments of fatigue, sleepiness, cognition and mood were completed by patients as part of usual care. Levels of daytime functioning and disability were quantified using symptom assessment tools, measuring fatigue (Chalder Fatigue Scale), sleepiness (Epworth Sleepiness Scale), cognitive functioning (Trail Making Test, Cognitive Failures Questionnaire), and mood (Hospital Anxiety and Depression Scale).
  
  
  RESULTS
  Hierarchical Regressions demonstrated that a shorter time since diagnosis, higher depression and longer wake time after sleep onset predicted 23.4% of the variance in fatigue severity (p <.001). Being male, higher depression and more afternoon naps predicted 25.6% of the variance in objective cognitive dysfunction (p <.001). Higher anxiety and depression and morning napping predicted 32.2% of the variance in subjective cognitive dysfunction (p <.001). When patients were classified into groups of mild and moderate sleepiness, those with longer daytime naps, those who mainly napped in the afternoon, and those with higher levels of anxiety, were more likely to be in the moderately sleepy group.
  
  
  CONCLUSIONS
  Napping, particularly in the afternoon is associated with poorer cognitive functioning and more daytime sleepiness in CFS. These findings have clinical implications for symptom management strategies.
authors.affiliation: Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, United Kingdom.
authors.forename: Zoe M
authors.initials: ZM
authors.lastname: Gotts
authors.affiliation: Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, United Kingdom.
authors.forename: Jason G
authors.initials: JG
authors.lastname: Ellis
authors.affiliation: Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, United Kingdom.
authors.forename: Vincent
authors.initials: V
authors.lastname: Deary
authors.affiliation: Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, United Kingdom.
authors.forename: Nicola
authors.initials: N
authors.lastname: Barclay
authors.affiliation: Institute of Cellular Medicine, Medical School, Newcastle University & Newcastle Hospitals NHS Foundation Trust and UK NIHR Biomedical Research Centre in Ageing, Newcastle-upon-Tyne, United Kingdom.
authors.forename: Julia L
authors.initials: JL
authors.lastname: Newton
mesh_terms: D000293:Adolescent; D000328:Adult; D000339:Affect / Q000502:physiology; D000368:Aged; D001007:Anxiety / Q000503:physiopathology; D003071:Cognition / Q000502:physiology*; D003863:Depression / Q000503:physiopathology; D005221:Fatigue / Q000473:pathology; D015673:Fatigue Syndrome, Chronic / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D057566:Self Report; D012890:Sleep / Q000502:physiology*; D011795:Surveys and Questionnaires; D014851:Wakefulness; D055815:Young Adult