title: Actigraphy in patients with seasonal affective disorder and healthy control subjects treated with light therapy.
abstract: BACKGROUND
  Abnormalities of the circadian rest-activity cycle are hypothesized to accompany the clinical picture of seasonal affective disorder (SAD). The purpose of this study was to investigate if bright light therapy (BLT) is able to reverse these disturbances.
  
  
  METHODS
  Seventeen SAD outpatients and 17 sex- and age-matched healthy control subjects were treated with BLT administered in the morning for 4 weeks. Activity levels were measured with wrist actigraphy.
  
  
  RESULTS
  SAD patients had 33% lower total (p = .031) and 43% lower daylight activity (p = .006) in week 1 compared with control subjects. The relative amplitude of the sleep-wake cycle was attenuated by 6% in patients (p = .025); they were phase delayed by 55 minutes (p = .023) and had significantly lower sleep efficiency (p = .030). Total (p = .002) and daylight activity (p = .001) increased after 4 weeks of treatment in SAD patients. Moreover, BLT led to increase of relative amplitude (p = .005), advance of delayed rhythms (p = .036), and improved sleep efficiency (p = .011) in patients. Intradaily stability, measuring the strength of coupling of the rhythm to external zeitgebers, increased by 9% both in patients and healthy control subjects (p = .032).
  
  
  CONCLUSIONS
  Treatment with BLT normalizes disturbed activity patterns and restores circadian rhythms in SAD patients. BLT might also stabilize the circadian rhythm in nondepressed individuals during the fall-winter season.
authors.affiliation: Department of General Psychiatry, Medical University of Vienna, Vienna, Austria. dietmar.winkler@meduniwien.ac.at
authors.forename: Dietmar
authors.initials: D
authors.lastname: Winkler
authors.forename: Edda
authors.initials: E
authors.lastname: Pjrek
authors.forename: Nicole
authors.initials: N
authors.lastname: Praschak-Rieder
authors.forename: Matthäus
authors.initials: M
authors.lastname: Willeit
authors.forename: Lukas
authors.initials: L
authors.lastname: Pezawas
authors.forename: Anastasios
authors.initials: A
authors.lastname: Konstantinidis
authors.forename: Jürgen
authors.initials: J
authors.lastname: Stastny
authors.forename: Siegfried
authors.initials: S
authors.lastname: Kasper
mesh_terms: D000204:Activity Cycles / Q000502:physiology / Q000528:radiation effects*; D000328:Adult; D000704:Analysis of Variance; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000528:radiation effects*; D010789:Phototherapy; D011569:Psychiatric Status Rating Scales; D016574:Seasonal Affective Disorder / Q000628:therapy*; D012890:Sleep / Q000502:physiology