title: Challenging the sleep homeostat: sleep in depression is not premature aging.
abstract: OBJECTIVE
  The close relationship between major depression and sleep disturbances led to the hypothesis of a deficiency in homeostatic sleep pressure in depression (S-deficiency hypothesis). Many observed changes of sleep characteristics in depression are also present in healthy aging, leading to the premise that sleep in depression resembles premature aging. In this study, we aimed at quantifying the homeostatic sleep-wake regulation in young women with major depression and healthy young and older controls under high sleep pressure conditions.
  
  
  METHODS
  After an 8-h baseline night nine depressed women, eight healthy young, and eight healthy older women underwent a 40-h sustained wakefulness protocol followed by a recovery night under constant routine conditions. Polysomnographic recordings were carried out continuously. Sleep parameters as well as the time course of EEG slow-wave activity (SWA) (EEG spectra range: 0.75-4.5 Hz), as a marker of homeostatic sleep pressure, were analyzed during the recovery night.
  
  
  RESULTS
  Young depressed women exhibited higher absolute mean SWA levels and a stronger response to sleep deprivation, particularly in frontal brain regions. In contrast, healthy older women exhibited not only attenuated SWA values compared to the other two groups, but also an absence of the frontal SWA predominance.
  
  
  CONCLUSIONS
  Homeostatic sleep regulation and sleep architecture in young depressed women are not equal to premature aging. Moreover, our findings demonstrate that young moderately depressed women exhibit no deficiency in the sleep homeostatic process S as predicted by the S-deficiency hypothesis, but, rather, live on an elevated level of homeostatic sleep pressure.
authors.affiliation: Centre for Chronobiology, Psychiatric University Clinics of the University of Basel, Wilhelm Kleinstrasse 27, CH-4025 Basel, Switzerland. silvia.frey@upkbs.ch
authors.forename: S
authors.initials: S
authors.lastname: Frey
authors.forename: A
authors.initials: A
authors.lastname: Birchler-Pedross
authors.forename: M
authors.initials: M
authors.lastname: Hofstetter
authors.forename: P
authors.initials: P
authors.lastname: Brunner
authors.forename: T
authors.initials: T
authors.lastname: Götz
authors.forename: M
authors.initials: M
authors.lastname: Münch
authors.forename: K
authors.initials: K
authors.lastname: Blatter
authors.forename: V
authors.initials: V
authors.lastname: Knoblauch
authors.forename: A
authors.initials: A
authors.lastname: Wirz-Justice
authors.forename: C
authors.initials: C
authors.lastname: Cajochen
mesh_terms: D000328:Adult; D000368:Aged; D019588:Aging, Premature / Q000503:physiopathology*; D016022:Case-Control Studies; D003865:Major Depressive Disorder / Q000503:physiopathology*; D004569:Electroencephalography; D005260:Female; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D008550:Melatonin / Q000032:analysis; D008875:Middle Aged; D017286:Polysomnography; D012463:Saliva / Q000737:chemistry; D012890:Sleep / Q000502:physiology*; D012894:Sleep Stages / Q000502:physiology; D055815:Young Adult
chemical_list: D008550:Melatonin