A study published in the Nov. 11 online issue of the Journal of Adolescent Health found that teens who stayed up late faced problems years later. The study analyzed 2,700 teens ages 13 to 18, about a third of whom went to bed after 11:30 p.m. on school nights or after 1:30 a.m. during the summer.
Six to eight years later, the study found that the night owls had lower grade-point averages than those who had gone to bed earlier, and reported more emotional issues, including sadness, irritability and depression, when they were 18 to 26 years old.
Interestingly, the teens who only stayed up late only in the summer did not have the same issues with academic performance.
Health experts say teens need about nine hours of sleep a night.