Lead researcher, Dr. Peter G. Polos of the JFK Medical Center sleep laboratory in Edison, N.J., surveyed 40 teens and young adults aged 8 to 22. All of the study participants had come to his office to discuss their sleep habits and 77% already had sleep issues, making the group skew toward the nocturnally active. But this clinical observation mirrors previous research, including one Belgian study in the journal Sleep that found that 60% of 13-to-15-year-olds used their cell phones to text or call after lights out, which led to increased fatigue. Other research has also linked lack of sleep to negative health consequences, including depression and weight gain, in teens. Polos presented his findings at the annual meeting of the American College of Chest Physicians held in Vancouver between Oct. 30 and Nov. 4.