How did reported depression, stress and suicide attempts differ by weekday sleep duration among Korean students?

Among students sleeping fewer than five hours, 33.4 percent reported depression and 57.9 percent frequent stress; the corresponding figures for those sleeping at least eight hours were 18.9 percent and 29.2 percent. Reported suicide attempts were 3.9 percent in the shortest-sleep group and 1.9 percent in the eight-hours-or-more group.

How did average weekday sleep change as Korean students moved from middle school into high school?

Average weekday sleep declined from 6.4 hours in students’ final year of middle school to 5.6 hours in their first year of high school, a 48-minute decrease in one year. It remained at 5.6 hours in the second and third years of high school.

What share of Korean high school students slept fewer than six hours on weekdays?

The National Youth Policy Institute found that 59.1 percent of high school students slept fewer than six hours on an average weekday. The findings came from responses by 54,170 middle and high school students nationwide.

1 in 4 Korean high schoolers sleep less than 5 hours on weekdays

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Summary

The National Youth Policy Institute reported Friday that 27.3 percent of Korean high school students slept less than five hours on weekdays, alongside higher reported rates of depression, stress and suicide attempts. The findings were based on responses from 54,170 middle and high school students nationwide. Average weekday sleep fell from 6.4 hours in the final year of middle school to 5.6 hours in the first year of high school, then remained at 5.6 hours in the second and third years.

Key Facts

Among students sleeping fewer than five hours on weekdays, 33.4 percent reported depression, compared with 18.9 percent of those sleeping at least eight hours.
Frequent stress was reported by 57.9 percent of students sleeping fewer than five hours, versus 29.2 percent of those sleeping at least eight hours.
Suicide attempts were reported by 3.9 percent of students in the shortest-sleep group and 1.9 percent of those sleeping at least eight hours.
Overall, 59.1 percent of high school students slept fewer than six hours on weekdays.
The drop from 6.4 to 5.6 hours of average weekday sleep between the final middle-school year and first high-school year amounted to 48 minutes.

By Jung Da-hyun

Published Nov 13, 2026 4:57 pm KST

High school students fill out answer sheets during a nationwide mock college entrance exam at a high school in Bupyeong District, Incheon, Oct. 20. Newsis

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 sleep group reporting having attempted suicide, roughly double the 1.9 percent recorded among those who slept eight hours or more.

Sleep duration dropped sharply as students entered high school, when academic workloads and pressure to prepare for college entrance exams typically increase.

Average weekday sleep fell from 6.4 hours in the final year of middle school to 5.6 hours in the first year of high school — a loss of 48 minutes in just one year.

Students continued to average just 5.6 hours of sleep through their second and third years of high school.

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