Limiting evening exposure to blue-light emitting screens on smartphones tablets and computers can reverse sleep problems and reduce symptoms of fatigue lack of concentration and bad mood in teenagers after just one week says a study. The researchers found that those who had more than four hours per day of screen time had on average 30 minutes later sleep onset and wake up times than those who recorded less than one hour per day of screen time as well as more symptoms of sleep loss. Adolescents increasingly spend more time on devices with screens and sleep complaints are frequent in