title: Immediate effects of an 8-h advance shift of the rest-activity cycle on 24-h profiles of cortisol.
abstract: To investigate the adaptation of plasma cortisol profiles to an abrupt phase advance of the rest-activity cycle, eight normal young subjects were submitted in a sleep laboratory to an 8-h advance shift of their sleep-wake and dark-light cycles. The shift was achieved by advancing bedtimes from 2300-0700 to 1500-2300. Blood samples were obtained at 20-min intervals for 68 consecutive hours. The shift resulted within 6-9 h in a 3- to 4-h advance of timings of the nadir of the cortisol profile and of the end of the quiescent period but had no immediate effect on the timing of cortisol acrophase. The quiescent period of cortisol secretion was shortened and fragmented. Thus a major advance shift achieved without enforcing sleep deprivation results in a rapid partial adaptation of the temporal profiles of cortisol but also in a marked disruption of the cortisol quiescent period. Sleep onset was consistently followed by a decrease in cortisol concentrations. Conversely, both sleep-wake and dark-light transitions were consistently associated with cortisol secretory pulses.
authors.affiliation: Laboratoire de Médecine Expérimentale and Centre d'Etudes des Rythmes Biologiques, Université Libre de Bruxelles, B-1070 Brussels, Belgium. acfz@ulb.ac.be
authors.forename: Anne
authors.initials: A
authors.lastname: Caufriez
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Moreno-Reyes
authors.forename: Rachel
authors.initials: R
authors.lastname: Leproult
authors.forename: Françoise
authors.initials: F
authors.lastname: Vertongen
authors.forename: Eve
authors.initials: E
authors.lastname: Van Cauter
authors.forename: Georges
authors.initials: G
authors.lastname: Copinschi
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000328:Adult; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D020179:Jet Lag Syndrome / Q000097:blood*; D008029:Lighting; D008297:Male; D012890:Sleep; D014851:Wakefulness
chemical_list: D006854:Hydrocortisone