title: Self-reported sleep duration, white blood cell counts and cytokine profiles in European adolescents: the HELENA study.
abstract: BACKGROUND
  Sleep patterns face important changes during adolescence. This can have implications for the immune system, which is regulated by the sleep-wake cycle; however, most studies relating sleep and immune system have been conducted on adults.
  
  
  OBJECTIVE
  To study the relationships between sleep duration, immune cell counts, and cytokines in European adolescents participating in the HELENA Cross-Sectional Study.
  
  
  METHODS
  Adolescents (12.5-17.5 years; n = 933; 53.9% girls) were grouped according to self-reported sleep duration into <8, 8-8.9 and ≥9 h/night. Blood samples were collected in the morning after an overnight fast to analyze counts of white blood cells (WBC), neutrophils, lymphocytes, monocytes, eosinophils, basophils, the lymphocyte subsets CD3(+), CD4(+), CD8(+), CD45RA(+), CD45RO(+), CD3(-)CD16(+)56(+) and CD19(+), and concentrations of cortisol, CRP, IL-1, IL-2, IL-4, IL-5, IL-6, IL-10, TNF-α and IFN-γ. Pro-/anti-inflammatory and Th1/Th2 cytokine ratios were calculated. Immune parameters were correlated to sleep duration and compared between the three groups.
  
  
  RESULTS
  Sleep duration was negatively associated with cortisol levels and WBC, neutrophil, monocyte, CD4(+) and CD4(+)CD45RO(+) counts; in girls it is also negatively associated with IL-5 and IL-6 levels. The 8-8.9 h/night group presented the highest IL-4 values and the lowest pro-/anti-inflammatory and Th1/Th2 cytokine ratios.
  
  
  CONCLUSIONS
  A sleep duration of 8-8.9 h/night was associated with a healthier immune profile in our adolescents.
authors.affiliation: Immunonutrition Research Group, Department of Metabolism and Nutrition, Institute of Food Science, Technology and Nutrition (ICTAN), Spanish National Research Council (CSIC), Madrid, Spain; School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, United Kingdom. Electronic address: f.perezdeherediabenedicte@ljmu.ac.uk.
authors.forename: Fátima
authors.initials: F
authors.lastname: Pérez de Heredia
authors.affiliation: Department of Physiology, Faculty of Biology, University of Murcia, Murcia, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Garaulet
authors.affiliation: Immunonutrition Research Group, Department of Metabolism and Nutrition, Institute of Food Science, Technology and Nutrition (ICTAN), Spanish National Research Council (CSIC), Madrid, Spain.
authors.forename: Sonia
authors.initials: S
authors.lastname: Gómez-Martínez
authors.affiliation: Immunonutrition Research Group, Department of Metabolism and Nutrition, Institute of Food Science, Technology and Nutrition (ICTAN), Spanish National Research Council (CSIC), Madrid, Spain.
authors.forename: Ligia E
authors.initials: LE
authors.lastname: Díaz
authors.affiliation: Unit for Preventive Nutrition, Department of Biosciences and Nutrition at Novum, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Julia
authors.initials: J
authors.lastname: Wärnberg
authors.affiliation: Department of Nutrition and Dietetics, University of Harokopio, Athens, Greece.
authors.forename: Odysseas
authors.initials: O
authors.lastname: Androutsos
authors.affiliation: Department of Public Health, Faculty of Medicine and Health Sciences, University of Ghent, UZ-Ghent, Gent, Belgium.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Michels
authors.affiliation: Department of Nutrition and Food Science, University of Bonn, Bonn, Germany; ImFINE Research Group, Department of Health and Human Performance, Faculty of Physical Activity and Sports Sciences-INEF, Technical University of Madrid, Madrid, Spain.
authors.forename: Christina
authors.initials: C
authors.lastname: Breidenassel
authors.affiliation: Department of Medical Physiology, School of Medicine, University of Granada, Granada, Spain.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Cuenca-García
authors.affiliation: Dietary Exposure Assessment Group, International Agency for Research on Cancer, Lyon, France.
authors.forename: Inge
authors.initials: I
authors.lastname: Huybrechts
authors.affiliation: Hôpital J de Flandre CHRU de Lille, Inserm U995, Faculté de Médecine, Université de Lille 2, Lille, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Gottrand
authors.affiliation: National Research Institute on Food and Nutrition, Rome, Italy.
authors.forename: Marika
authors.initials: M
authors.lastname: Ferrari
authors.affiliation: GENUD (Growth, Exercise, Nutrition and Development) Research Group, University of Zaragoza, Zaragoza, Spain.
authors.forename: Alba M
authors.initials: AM
authors.lastname: Santaliestra-Pasías
authors.affiliation: Preventive Medicine and Nutrition Unit, School of Medicine, University of Crete, Heraklion, Greece.
authors.forename: Anthony
authors.initials: A
authors.lastname: Kafatos
authors.affiliation: Department of Pediatrics, University of Pécs, Pécs, Hungary.
authors.forename: Denes
authors.initials: D
authors.lastname: Molnár
authors.affiliation: Unit for Preventive Nutrition, Department of Biosciences and Nutrition at Novum, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Michael
authors.initials: M
authors.lastname: Sjöstrom
authors.affiliation: Department of Pediatrics, Division of Clinical Nutrition and Prevention, Medical University of Vienna, Vienna, Austria.
authors.forename: Kurt
authors.initials: K
authors.lastname: Widhalm
authors.affiliation: GENUD (Growth, Exercise, Nutrition and Development) Research Group, University of Zaragoza, Zaragoza, Spain; Department of Preventive Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Luis A
authors.initials: LA
authors.lastname: Moreno
authors.affiliation: Immunonutrition Research Group, Department of Metabolism and Nutrition, Institute of Food Science, Technology and Nutrition (ICTAN), Spanish National Research Council (CSIC), Madrid, Spain.
authors.forename: Ascensión
authors.initials: A
authors.lastname: Marcos
mesh_terms: D000293:Adolescent; D016207:Cytokines / Q000097:blood* / Q000502:physiology; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood / Q000502:physiology; D007378:Interleukins / Q000097:blood / Q000502:physiology; D007958:Leukocyte Count; D016131:Lymphocyte Subsets / Q000502:physiology; D008297:Male; D012737:Sex Factors; D012890:Sleep / Q000276:immunology* / Q000502:physiology; D011795:Surveys and Questionnaires
chemical_list: D016207:Cytokines; D007378:Interleukins; D006854:Hydrocortisone
keywords: Adolescents; Cytokine balance; Gender differences; Immune cell profile; Inflammation; Sleep duration; Th1/Th2