From Harvard U: More about how kids really do need their sleep.

http://www.ncbi.nlm.nih.gov/pubmed/22331514

Sleep Breath. 2012 Jan 31. [Epub ahead of print]
Effects of exercise and nutritional intake on sleep architecture in adolescents.
Awad KM, Drescher AA, Malhotra A, Quan SF.
Source
Division of Sleep Medicine, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA, 02115, USA, kmawad@partners.org.

Abstract
PURPOSE:
Few studies have evaluated the relationship between sleep architecture and body mass index (BMI), nutrition, and physical activity in children. This study determined the relationship between sleep architecture and diet and exercise.

METHODS:
Three hundred nineteen Caucasian and Hispanic children aged 10 to 17 years participated in the follow-up assessment of the Tucson Children's Assessment of Sleep Apnea study. The children and parents completed several questionnaires on dietary habits, amount of physical activity, and sleep habits. Subjects also underwent a home polysomnogram to characterize their sleep.

RESULTS:
Significant bivariate correlations were noted between stage II sleep percentage and the following: BMI (r = 0.246, p < 0.01), estimated total recreational energy expenditure (r = 0.205, p < 0.01), vigorous activity (r = 0.130, p = 0.009), and total estimated activity (r = 0.148, p = 0.009). In girls, significant correlations were noted between stage II percentage sleep and BMI score (r = 0.279, p < 0.01). Also in girls, significant negative correlation was noted between rapid eye movement (REM) sleep percentage and total fat intake (r = -0.168, p = 0.039). In boys, significant correlations were again seen between stage II percentage sleep and the following: BMI score (r = 0.218, p = 0.005), estimated total recreational energy expenditure (r = 0.265, p = 0.001), vigorous activity (r = 0.209, p = 0.008), and total estimated activity (r = 0.206, p = 0.010). When controlling for BMI percentile and age, significant bivariate correlation was also noted between REM sleep percentage and total fat intake (r = 0.176, p = 0.034) in boys.

CONCLUSIONS:
BMI and exercise were associated with increases in stage II sleep. In girls, total fat intake was associated with a reduction in REM sleep, while in boys (after controlling for BMI percentile and age), total fat intake correlated with REM sleep.