We aimed to describe the sleep patterns in Spanish adolescents and to examine the relationships of sleep duration and morning tiredness with participation in leisure-time physical-sporting activities (LT-PA) and television (TV) watching. Sleep duration, morning tiredness, participation in LT-PA and time spent on watching TV were reported by 2,179 (1,139 females) Spanish adolescents (AVENA study). Data were analyzed by binary logistic regression. One-fifth of the adolescents reported insufficient night sleep (<8 h) on school days. The review of the literature (30 studies) showed that the Spanish adolescents sleep as long as adolescents from central Europe, and longer than those from other Mediterranean countries, South Africa, Asia and North America. Insufficient sleep duration doubled the odds of excessive TV watching (≥3 h/day) in males, regardless of morning tiredness (OR 2.15, 95% CI 1.42-3.27). Morning tiredness reduced the odds of participating in any LT-PA in both males and females (0.49, 0.34-0.70 and 0.49, 0.35-0.69, respectively), and increased the odds of excessive TV watching in females, regardless of sleep duration (2.49, 1.64-3.79). We conclude that non-participation in LT-PA is associated with morning tiredness in male and female adolescents, while excessive TV watching is more associated with short sleep or morning tiredness depending on gender.