In China, 38 percent of people suffer from various kinds of sleep problems, compared to the world average of 27 percent, according to the Chinese Sleep Research Society (CSRS).

Currently there are over 80 kinds of sleep disorders, and most people are not aware that sleep disorder can trigger heart disease, according to CSRS on March 16, 2013.

Every year, more than 1 million people die of coronary disease, and 30 percent of them suffer sudden death between midnight and 6 am. Every day, more than 3,000 people die of disease related to sleep apnea.

Sleep apnea can raise the death risk of heart disease, said Han Fang, head of CSRS.

The annual World Sleep Day is March 21, and this year the theme in China is "Focus on sleep, focus on heart".