Lack of sleep among children and teenagers in China has worsened in the past decade, with more than 80 percent getting insufficient sleep on school days, a new report has found.

Chinese youngsters snooze 7.8 hours a night on average on school days, down 0.3 hours from 2009, according to the report released on Monday by the Chinese Academy of Sciences' Institute of Psychology.

Researchers surveyed more than 15,800 students from Henan, Hebei and Guangdong provinces from April to July, asking what time they go to bed and wake up on days they take offline classes on campus.

Only 46.4 percent of them sleep for at least 8 hours, compared with 47.4 percent in 2009.

According to an action plan laying out measures to be taken from 2019 to 2030 to promote the health of citizens, primary school students are recommended to get a minimum of 10 hours of sleep a night. For junior high school and senior high school students, the recommended sleep durations per night are 9 and 8 hours respectively.

By this set of standards, more than 95 percent of students from primary schools, nearly 91 percent at junior high and 84 percent at senior high, did not get enough sleep on school days, heightening the risk of them developing cognitive, mental and physical health problems, the report said.

Hou Jinqin, a researcher at the National Institute of Education Sciences who co-authored the study, suggested local authorities implement measures instructed by the Ministry of Education, such as lessening academic burdens, postponing start times at school and encouraging children to be enrolled at institutions closer to home, in order to prolong sleeping hours.

In terms of the COVID-19 outbreak's impact on sleep, she said available research overseas shows school closures forced by the COVID-19 epidemic have added two hours of sleep to young students studying at home.

In China, some studies have revealed no marked differences in sleeping patterns of students before and after school reopened, she added.