title: Circadian interleukin-6 secretion and quantity and depth of sleep.
abstract: Patients with pathologically increased daytime sleepiness and fatigue have elevated levels of circulating interleukin-6 (IL-6). The latter is an inflammatory cytokine, which causes sickness manifestations, including somnolence and fatigue, and activation of the hypothalamic-pituitary-adrenal axis. In this study, we examined: 1) the relation between serial measurements of plasma IL-6 and quantity and depth of sleep, evaluated by polysomnography; and 2) the effects of sleep deprivation on the nyctohemeral pattern of IL-6 secretion. Eight healthy young male volunteers were sampled for 24 h twice, at the baseline state, after a normal night's sleep and after total overnight sleep deprivation. At the baseline state, IL-6 was secreted in a biphasic circadian pattern with two nadirs at 0800 and 2100 and two zeniths at 1900 and 0500 (P < 0.01). The baseline amount of sleep correlated negatively with the overall daytime secretion of the cytokine (P < 0.05). Also, depth of sleep at baseline correlated negatively with the postdeprivation increase of daytime secretion of IL-6 (P < 0.05). Sleep deprivation changed the temporal pattern of circadian IL-6 secretion but not the overall amount. Indeed, during the post-deprivation period, the mean daytime (0800-2200 h) levels of IL-6 were significantly higher (P < 0.05), whereas the nighttime (2200-0600 h) levels were lower than the predeprivation values. Thus, sleep-deprived subjects had daytime oversecretion and nighttime under-secretion of IL-6; the former might be responsible for their daylong somnolence and fatigue, the latter for the better quality (depth) of their sleep. These data suggest that a good night's sleep is associated with decreased daytime secretion of IL-6 and a good sense of well-being and that good sleep is associated with decreased exposure of tissues to the proinflammatory and potentially detrimental actions of IL-6. Sleep deprivation increases daytime IL-6 and causes somnolence and fatigue during the next day, whereas postdeprivation decreases nighttime IL-6 and is associated with deeper sleep.
authors.affiliation: Sleep Research and Treatment Center, Department of Psychiatry, Pennsylvania State University, Hershey 17033, USA. axv3@psu.edu
authors.forename: A N
authors.initials: AN
authors.lastname: Vgontzas
authors.forename: D A
authors.initials: DA
authors.lastname: Papanicolaou
authors.forename: E O
authors.initials: EO
authors.lastname: Bixler
authors.forename: A
authors.initials: A
authors.lastname: Lotsikas
authors.forename: K
authors.initials: K
authors.lastname: Zachman
authors.forename: A
authors.initials: A
authors.lastname: Kales
authors.forename: P
authors.initials: P
authors.lastname: Prolo
authors.forename: M L
authors.initials: ML
authors.lastname: Wong
authors.forename: J
authors.initials: J
authors.lastname: Licinio
authors.forename: P W
authors.initials: PW
authors.lastname: Gold
authors.forename: R C
authors.initials: RC
authors.lastname: Hermida
authors.forename: G
authors.initials: G
authors.lastname: Mastorakos
authors.forename: G P
authors.initials: GP
authors.lastname: Chrousos
mesh_terms: D000328:Adult; D002940:Circadian Rhythm; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism*; D008297:Male; D012890:Sleep; D012892:Sleep Deprivation
chemical_list: D015850:Interleukin-6