One in four high school students in Korea gets less than five hours of sleep a night on weekdays, with those sleeping fewer hours reporting higher rates of stress, depression and suicidal thoughts. According to the National Youth Policy Institute on Friday, 27.3 percent of high school students slept less than five hours on average during weekdays, while 59.1 percent got fewer than six hours. The findings were based on responses from 54,170 middle and high school students nationwide. The study found that students who slept less tended to report poorer mental health. Among those getting fewer than five hours of sleep on weekdays, 33.4 percent reported experiencing depression, compared with 18.9 percent of those sleeping eight hours or more — a difference of 14.5 percentage points. Students sleeping less than five hours were also nearly twice as likely to experience high levels of stress, with 57.9 percent reporting frequent stress, compared with 29.2 percent of those getting at least eight hours of sleep. The gap extended to suicide attempts, with 3.9 percent of students in the shortest