According to nearly 5,000 subjects aged 28 to 38, Dr. Anthony from Harvard Medical School, who led the survey, disclosed 75 percent suffered or suffer from sleep disorders. He points out nightlife and bad habits are the main causes, as well as occupational pressures.

The survey shows 8.6% of the Shanghai people sleep uncomfortably on hard beds or tatamis because of discomfort in the waist, shoulder and neck.

Nineteen percent of the respondents have fostered bad habits since childhood, such as clutching pillows or lying face-down. They candidly admit they can be frequently awakened by nightmares.

In addition, compared to other cities, young adults in Shanghai are accustomed to nightlife, which is very disadvantageous to the amount of sleep every night if activities last late into the evening.

The study also reveals the relationship between the weather and sleep impediments. In summer, the proportion of people who are susceptible to sleep disorders increases. Specialists explain when the temperature creeps above 25 degrees Celsius at night, the central nervous system is more easily stimulated, which could be one explanation for the responses. In addition, nights are shorter in the summer. The earlier sunset arouses the brain at an early time. Consequently, it is difficult for people who are accustomed to nightlife to have a sound sleep.