title: Altered skin-temperature regulation in narcolepsy relates to sleep propensity.
abstract: OBJECTIVE
  In healthy subjects, sleep propensity increases when the distal skin temperature increases relative to the proximal skin temperature. This increase results from increased blood flow in the skin of the extremities and is, among other factors, controlled by the hypothalamic circadian clock, as is sleep. Because narcolepsy is characterized by hypothalamic alterations, we studied skin temperature in narcoleptic patients in relation to their characteristically increased sleep propensity during the day.
  
  
  METHODS
  Distal and proximal skin temperature and their gradient (DPG) were measured during a Multiple Sleep Latency Test. This allowed temperature to be studied during wakefulness, at sleep onset and during sleep.
  
  
  METHODS
  Tertiary narcolepsy referral center in a university hospital.
  
  
  METHODS
  Fifteen unmedicated narcolepsy patients with cataplexy and 15 controls.
  
  
  METHODS
  None.
  
  
  RESULTS
  In subjects in the waking state, DPG was higher in narcoleptics than in controls throughout the day (time by group interaction, p < .0001), due to increased distal skin temperature and decreased proximal skin temperature. The increase in DPG was related to a shorter subsequent sleep-onset latency (p = .02). Once asleep, narcoleptics maintained their elevated distal skin temperature and DPG (p < .0001), whereas proximal skin temperature increased to reach normal levels.
  
  
  CONCLUSIONS
  This is the first demonstration of a dramatic alteration of daytime skin temperature control in narcolepsy. Even awake narcoleptic patients showed a DPG higher than that which healthy controls achieve when asleep. This observation suggests that hypocretin deficiency in narcolepsy affects skin-temperature regulation and invites further examination. Skin-temperature control might ultimately even have therapeutic implications for the alleviation of narcoleptic symptoms.
authors.affiliation: Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA Amsterdam, The Netherlands. r.fronczek@lumc.nl
authors.forename: Rolf
authors.initials: R
authors.lastname: Fronczek
authors.forename: Sebastiaan
authors.initials: S
authors.lastname: Overeem
authors.forename: Gert Jan
authors.initials: GJ
authors.lastname: Lammers
authors.forename: J Gert
authors.initials: JG
authors.lastname: van Dijk
authors.forename: Eus J W
authors.initials: EJ
authors.lastname: Van Someren
mesh_terms: D000328:Adult; D001833:Body Temperature Regulation / Q000502:physiology*; D002385:Cataplexy / Q000503:physiopathology; D002940:Circadian Rhythm / Q000502:physiology; D005260:Female; D005528:Foot / Q000098:blood supply; D006225:Hand / Q000098:blood supply; D006801:Humans; D007031:Hypothalamus / Q000503:physiopathology; D008297:Male; D009290:Narcolepsy / Q000503:physiopathology*; D017286:Polysomnography; D011930:Reaction Time / Q000502:physiology; D012016:Reference Values; D012039:Regional Blood Flow / Q000502:physiology; D012867:Skin / Q000098:blood supply; D012881:Skin Temperature / Q000502:physiology*; D012890:Sleep / Q000502:physiology; D014851:Wakefulness / Q000502:physiology