title: Sleep-wake behavior in chronic fatigue syndrome.
abstract: OBJECTIVE
  Disturbances of the internal biological clock manifest as fatigue, poor concentration, and sleep disturbances-symptoms reminiscent of chronic fatigue syndrome (CFS) and suggestive of a role for circadian rhythm disturbance in CFS. We examined circadian patterns of activity, sleep, and cortisol secretion in patients with CFS.
  
  
  METHODS
  Case-control study, 5-day behavioral observation.
  
  
  METHODS
  Natural setting/home environment
  
  
  METHODS
  15 patients with CFS and 15 healthy subjects of similar age, sex, body mass index (BMI), and activity levels.
  
  
  METHODS
  N/A.
  
  
  METHODS
  Self-report questionnaires were used to obtain medical history and demographic information and to assess health behaviors, somatic and psychological symptoms, and sleep quality. An actiwatch accelerometer recorded activity and sleep patterns over 5 days with concurrent activity and symptom logs. Diurnal salivary cortisol secretion was measured. Additionally, overnight heart rate monitoring and pain sensitivity assessment was undertaken.
  
  
  RESULTS
  Ratings of symptoms, disability, sleep disturbance, and pain sensitivity were greater in patients with CFS. No between-group differences were found in the pattern or amount of sleep, activity, or cortisol secretion. Afternoon activity levels significantly increased evening fatigue in patients but not control subjects. Low nocturnal heart rate variability was identified as a biological correlate of unrefreshing sleep.
  
  
  CONCLUSIONS
  We found no evidence of circadian rhythm disturbance in CFS. However, the role of autonomic activity in the experience of unrefreshing sleep warrants further assessment. The activity symptom-relationship modelled here is of clinical significance in the approach to activity and symptom management in the treatment of CFS.
authors.affiliation: School of Psychiatry, University of NSW, Sydney, Australia.
authors.forename: Khairunnessa
authors.initials: K
authors.lastname: Rahman
authors.forename: Alexander
authors.initials: A
authors.lastname: Burton
authors.forename: Sally
authors.initials: S
authors.lastname: Galbraith
authors.forename: Andrew
authors.initials: A
authors.lastname: Lloyd
authors.forename: Ute
authors.initials: U
authors.lastname: Vollmer-Conna
mesh_terms: D056044:Actigraphy; D000328:Adult; D016022:Case-Control Studies; D002940:Circadian Rhythm / Q000502:physiology*; D015673:Fatigue Syndrome, Chronic / Q000503:physiopathology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis; D008297:Male; D010146:Pain / Q000503:physiopathology; D010147:Pain Measurement; D012044:Regression Analysis; D012463:Saliva / Q000737:chemistry; D012890:Sleep / Q000502:physiology; D007319:Sleep Initiation and Maintenance Disorders / Q000503:physiopathology; D011795:Surveys and Questionnaires
chemical_list: D006854:Hydrocortisone