The less sleep teenagers get, the more likely they are to engage in risky and illegal behavior, according to a new study published in Preventive Medicine.

While staying up late on school nights or just in general is not unusual for teens, the study found that at least two-thirds of American teens get less than eight of hours shut-eye a day, which leads to a greater risk of smoking, drinking, sexual activity, use of illegal drugs such as marijuana, and increased feelings of sadness or helplessness.

Fighting and “consideration of suicide” are also health risk behaviors associated with lack of sleep, according to the study’s author, Lela R. McKnight-Eily of the Centers for the Disease Control and Prevention.

While the effects of sleep deprivation on teen behavior has been documented many times before, McKnight-Eily said the study is the first large-scale effort of its kind to use Youth Risk Behavior Survey data, which is compiled every two years based on information provided by students nationwide in grades 9-12. The study involved more than 12,000 students who were asked questions for the first time about their sleep habits.

The researchers found that the lack of sufficient sleep – defined as eight hours – can be associated with 10 out of 11 key behaviors that can lead to serious health problems and even suicide.