More than 40 percent of Chinese people suffer from sleep disorders, but less than 1 percent have been diagnosed or treated, experts said.

Working people, particularly shift workers in cities who have fast-paced lifestyles, have the highest risk of sleep problems, said Han Fang, director of the sleep center under the Peking University People's Hospital and vice-president of the Chinese Sleep Research Society.

The problems, if not properly addressed, will affect their working efficiency and social productivity.

"As Chinese society is rapidly aging and people are getting fatter, sleep problems will surely rise," Han said on Tuesday at the 2012 World Sleep Forum held by the Ministry of Health and the Chinese Sleep Research Society to mark World Sleep Day, which falls on March 21 every year.

Sleep disorders are medical disorders of sleeping patterns, and some sleep disorders are serious enough to interfere with normal physical, mental and emotional functioning of the sufferers, according to Christian Guilleminault, professor of psychiatry and behavioral sciences and neurology at Stanford University Medical School in the United States.

"Intervention helps with both people's health and the economy, given that errors, lapses and fatigue due to sleep disorders cost the US $150 billion each year," he said.

In China, more than 30 percent of people have suffered from insomnia - the most common form of sleep disorder - at least once, Han said.

A teacher shows children the correct sleeping position in a kindergarten in Kaifeng, Henan province, on Monday to mark World Sleep Day, which falls on Wednesday. Kai Feng / for China Daily