Original Article Sleep duration and emerging cardiometabolic risk markers in adolescents. The AFINOS Study David Martinez-Gomez a,b,⇑ , Joey C. Eisenmann c,d , Sonia Gomez-Martinez a , Emily E. Hill c , Belen Zapatera a , Oscar L. Veiga b , Ascension Marcos a , for the AFINOS Study Group 1 a Immunonutrition Research Group, Department of Metabolism and Nutrition, Institute of Food Science, Technology and Nutrition (ICTAN), Spanish National Research Council (CSIC), Madrid, Spain b Department of Physical Education, Sport and Human Movement, Facultad de Formación del Profesorado y Educación, Universidad Autonoma de Madrid, Madrid, Spain c Department of Kinesiology, Michigan State University, East Lansing, MI, USA d Department of Pediatrics and Human Development, Michigan State University, East Lansing, MI, USA article info Article history: Received 19 January 2011 Received in revised form 2 May 2011 Accepted 7 May 2011 Available online 28 October 2011 Keywords: Sleep Adolescence Inflammation Endothelial function C-reactive protein Physical activity abstract Objective: To examine the associations between sleep duration and emerging inflammatory and endothe- lial function risk factors in adolescents. Methods: This study included a total of 183 (88 girls) adolescents, aged 13–17 years, without diagnosed sleep-related disorders. White blood cell counts, C-reactive protein (CRP), complement factors 3 and 4, interleukin-6, adiponectin, leptin, inter-cellular adhesion molecule 1, vascular cell adhesion molecule-1, E-selectin, L-selectin, and plasminogen activator inhibitor-1 were measured. Sleep duration and sleep- related disorders were obtained by self-report and moderate-to-vigorous physical activity (MVPA) was objectively measured by accelerometer. Body mass index (BMI) was calculated from measured height and weight. Results: A significant inverse association between sleep duration and CRP (b = À0.17, P = 0.024) existed only after controlling for sex, age, and pubertal status. The results did not change when MVPA was included into the model. However, the association of sleep duration with CRP was slightly attenuated when BMI was included in the model, though it remained significant (b = À0.15, P = 0.044). Conclusion: Short sleep duration during adolescence might play an important and independent role in cardiovascular and metabolic diseases through CRP. Ó 2011 Elsevier B.V. All rights reserved. 1. Introduction Over four decades of evidence indicate a strong inverse association between short nighttime sleep duration and all-cause mortality and, particularly, cardiovascular mortality [1–3]. In addi- tion, several studies have shown that nighttime sleep duration might play a key role in cardiovascular morbidity (e.g., atheroscle- rosis and coronary events) and type 2 diabetes [3–6]. In young people, however, little is known regarding the poten- tial effects of sleep quantity on cardiometabolic risk factors (e.g., hypertension, lipid abnormalities, and impaired glucose tolerance). According to the limited evidence available, the associations be- tween sleep duration and the conventional cardiometabolic risk factors (e.g., hypertension, lipid abnormalities, and impaired glu- cose tolerance) in youth might be mediated by adiposity, since sev- eral studies have shown a strong relationship between sleep duration and obesity in children and adolescents [7–10]. Recent studies have highlighted the ability of novel cardiomet- abolic biomarkers to clarify some of the unexplained variability in the development of atherosclerosis and type 2 diabetes [11–13]. The associations between sleep duration and emerging cardiomet- abolic risk factors such as low-grade inflammation and endothelial dysfunction markers (e.g., leukocytes, inflammatory proteins, adhesion molecules, and cytokines) is largely unknown in youth 1389-9457/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.sleep.2011.05.009 ⇑ Corresponding author at: Immunonutrition Research Group, Department of Metabolism and Nutrition, Institute of Food Science, Technology and Nutrition (ICTAN), Consejo Superior de Investigaciones Científicas, Calle José Antonio Novais, 10, 28040 Madrid, Spain. Tel.: +34 91 549 23 00x296/297; fax: 34 91 549 36 27. E-mail address: d.martinez@uam.es (D. Martinez-Gomez). 1 AFINOS Study Group:Study coordinator: Marcos A. Sub-study coordinators: Calle ME, Villagra A, Marcos A. Sub-study 1: Calle ME, Regidor E, Martínez-Hernández D, Esteban-Gonzalo L. Department of Preventive Medicine and Public Health, Univers- idad Complutense de Madrid, E-28040 Madrid, Spain. Sub-study 2: Villagra A, Veiga OL, del-Campo J, Moya JM, Martínez-Gómez D, Zapatera B. Department of Physical Education, Sport and Human Movement, Facultad de Formación del Profesorado y Educación, Universidad Autonoma de Madrid, E-28049 Madrid, Spain. Sub-study 3: Marcos A, Gómez-Martínez S, Nova E, Wärnberg J, Romeo J, Diaz LE, Pozo T, Puertollano MA, Martínez-Gómez D, Zapatera B, Veses A. Immunonutrition Research Group, Department of Metabolism and Nutrition, Institute of Food Science, Technol- ogy and Nutrition (ICTAN), Instituto del Frio, Spanish National Research Council (CSIC), E-28040 Madrid, Spain. Sleep Medicine 12 (2011) 997–1002 Contents lists available at SciVerse ScienceDirect Sleep Medicine journal homepage: www.elsevier.com/locate/sleep