title: Sleep restriction increases white blood cells, mainly neutrophil count, in young healthy men: a pilot study.
abstract: OBJECTIVE
  This study examines the effects of sleep restricted to four hours for three consecutive nights on blood parameters, known to be associated with cardiovascular risk, in young healthy men.
  
  
  METHODS
  Eight young healthy men (age 24.5 +/- 3.3 years) were studied in the sleep restricted group. Nine young healthy men (age 24 +/- 2 years) were included in the control group and spent the days and nights in the sleep lab, while sleeping eight hours/night. One baseline night was followed by three nights of sleep restriction to four hours and by one recovery night of eight hours. Blood samplings were performed after the baseline night and after the third night of sleep restriction or without restriction for the control group.
  
  
  RESULTS
  A significant increase in white blood cells (WBC) (5.79 +/- 1.05 vs. 6.89 +/- 1.31 10(3) cell/microl, p = 0.03), and neutrophils (3.17 +/- 0.69 vs 4.24 +/- 0.97 10(3) cell/microl, p = 0.01) was observed after the third night of sleep restriction. Other blood parameters were not affected. No significant variation was observed in the control group.
  
  
  CONCLUSIONS
  Sleep restriction affected WBC count, mainly neutrophils, considered as risk factor for cardiovascular disease. Stress induced by the short term sleep restriction could be involved in this observation.
authors.affiliation: Laboratory of Experimental Medicine (ULB 222 Unit), CHU de Charleroi Vésale Hospital, Université Libre de Bruxelles, Rue de Gozée 706, Montigny-le-Tilleul, Belgium.
authors.forename: Karim Zouaoui
authors.initials: KZ
authors.lastname: Boudjeltia
authors.forename: Brice
authors.initials: B
authors.lastname: Faraut
authors.forename: Patricia
authors.initials: P
authors.lastname: Stenuit
authors.forename: Maria José
authors.initials: MJ
authors.lastname: Esposito
authors.forename: Michal
authors.initials: M
authors.lastname: Dyzma
authors.forename: Dany
authors.initials: D
authors.lastname: Brohée
authors.forename: Jean
authors.initials: J
authors.lastname: Ducobu
authors.forename: Michel
authors.initials: M
authors.lastname: Vanhaeverbeek
authors.forename: Myriam
authors.initials: M
authors.lastname: Kerkhofs