Inadequate sleep is linked to obesity in adolescents— according to a study on teenagers from nine countries in Europe. Short sleepers had larger BMIs (proportion of weight to height), body fat, waist and hip circumferences, watched more television and exercised less than kids who slept at least eight hours a night. Sleep-deprived kids also ate fewer fruits, vegetables and fish. The problem was more significant in girls than boys.
Sleep problems disrupt metabolic and hormonal control systems that regulate bodyweight. This results in poor blood sugar control, insulin resistance, stress-related increases in cortisol, increased levels of ghrelin (regulates appetite), decreased levels of leptin (regulates appetite and metabolic rate) and increased hunger. Sleep loss promotes nighttime eating and biases the metabolism toward fat storage instead of fat burning.
Large population studies and laboratory experiments established a strong link between poor sleep habits and body fat accumulation. Adolescents who sleep less than eight hours a night eat more and exercise less. (International Journal of Obesity, 35: 1308-1317)