title: Cerebral oxygen metabolism and cerebral blood flow in man during light sleep (stage 2).
abstract: We measured cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) during light sleep (stage 2) in 8 young healthy volunteers using the Kety-Schmidt technique with 133Xe as the inert gas. Measurements were performed during wakefulness and light sleep as verified by standard polysomnography. Unlike our previous study in man showing a highly significant 25% decrease in CMRO2 during deep sleep (stage 3-4) we found a modest but statistically significant decrease of 5% in CMRO2 during stage 2 sleep. Deep and light sleep are both characterized by an almost complete lack of mental activity. They differ in respect of arousal threshold as a stronger stimulus is required to awaken a subject from deep sleep as compared to light sleep. Our results suggest that during non-rapid eye movement sleep cerebral metabolism and thereby cerebral synaptic activity is correlated to cerebral readiness rather than to mental activity.
authors.affiliation: Department of Clinical Physiology and Nuclear Medicine, Bispebjerg Hospital, Copenhagen, Denmark.
authors.forename: P L
authors.initials: PL
authors.lastname: Madsen
authors.forename: J F
authors.initials: JF
authors.lastname: Schmidt
authors.forename: S
authors.initials: S
authors.lastname: Holm
authors.forename: S
authors.initials: S
authors.lastname: Vorstrup
authors.forename: N A
authors.initials: NA
authors.lastname: Lassen
authors.forename: G
authors.initials: G
authors.lastname: Wildschiødtz
mesh_terms: D000328:Adult; D001923:Brain Chemistry / Q000502:physiology*; D002245:Carbon Dioxide / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology*; D012890:Sleep / Q000502:physiology*; D012894:Sleep Stages / Q000502:physiology*; D014980:Xenon Radioisotopes
chemical_list: D014980:Xenon Radioisotopes; D002245:Carbon Dioxide