Nearly 80 percent of Chinese school students do not get enough sleep, Beijing News reported Monday.

The sleep time for primary and middle school students has been decreasing consecutively for a number of years, according to the Research Report on Ten-Year Development of Chinese Youth and Children (1999-2010) released by China Youth and Children Research Center.

The average sleep time for primary children on school days is about seven hours and 37 minutes in 2010, one hour and 22 minutes less than in 2005. The figure at weekends is seven hours and 49 minutes, one hour and 47 minutes less compared to 2005.

Chu Hongqi, professor at Beijing Normal University, attributed this trend to students being overburdened with study and the pressure from parents and schools to achieve higher results.

Students in primary and middle schools often have after-school classes to help them get into a better school.