1. ^*Louis Pasteur University of Strasbourg, Medical Faculty, Strasbourg, France
2. ^†Mission de Promotion de la Santé auprès des Elèves, Inspection Académique du Bas-Rhin, Strasbourg, France

Correspondence: Chantal Simon EA 1801, Epidemiology of Cardiovascular Diseases and Cancers, Influence of Nutrition and Physical Inactivity, Louis Pasteur University of Strasbourg–Medical Faculty, 4 rue Kirschleger, 67085 Strasbourg Cedex, France. E-mail: chantal.simon@medecine.u-strasbg.fr

^**The costs of publication of this article were defrayed, in part, by the payment of page charges. This article must, therefore, be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

Received 1 September 2006; Accepted 21 February 2007.

Abstract

Objective: The objective was to determine if having a television (TV) in the bedroom is associated with physical activity (PA), TV/video viewing, and adiposity throughout adolescence.

Research Methods and Procedures: Longitudinal data (September 2002 through June 2005) were analyzed of 379 initially 12-year-old French adolescents participating as controls in the Intervention Centered on Adolescents' Physical activity and Sedentary behavior (ICAPS). Presence of a TV set in the bedroom (TV_bedroom) and leisure activities were obtained by questionnaire. There was annual assessment of BMI, waist circumference, and body fat by bioimpedance.

Results: In boys but not girls, baseline TV_bedroom was associated with higher TV/video viewing over time [ odds ratio (OR) of high TV/video = 1.87; 95% confidence interval, 1.2 to 2.8] and less no-sport club participation (OR = 0.59; 95% confidence interval, 0.35 to 1.0). Both boys and girls with baseline TV_bedroom had lower reading time (p < 0.0001 in boys; p = 0.04 in girls), while PA did not differ according to TV_bedroom for boys or for girls. For boys only, baseline TV_bedroom was associated with higher BMI (mean BMI over time 20.5 0.5 vs. 19.0 0.5 kg/m²; p = 0.001), waist circumference (70.9 0.9 vs. 67.2 0.8 cm; p < 0.001), and body fat (15.9 0.9% vs. 13.5 0.9% ; p < 0.001), without interaction with time. These relationships remained significant after adjustment for socioeconomic status. TV/video viewing explained 26% , 42% , and 36% of the relationships of TV_bedroom with BMI, waist circumference, and body fat, respectively, while addition of other leisure activities in the models only marginally reduced the effects.

Discussion: These results suggest the importance of keeping TV out of an adolescent's bedroom from an obesity prevention perspective but show gender differences.