More than 60 percent of people born in 1990s do not get enough sleep, with those living in Beijing among those waking up earliest, a survey shows.

Chinese Medical Doctor Association’s sleep medicine specialized committee released the data from the lastest survey about?sleeping patterns across the world on Sunday, three days before the 18th World Sleep Day on March 21, according to Beijing Evening News.

The survey on Chinese born in 1990s showed their average sleep time is 7.5 hours. More than 60 percent of them have difficulty falling asleep and 12.2 percent have insomnia.

About 31 percent of them take more than 30 minutes to sleep, and 0.9 percent need sleep medicine.

As for their sleep habits, 31.1 percent of post-90s people sleep late and wake up late, while 30.9 percent sleep late and wake up early and only 17.5 percent sleep early and wake up early. Moreover, only 28.2 percent wake up naturally.

Nationwide, post-90s people living in Shanghai sleep earliest, while those in Shenzhen are most unwilling to go to bed. As a contrast to Beijing, Zhuhai is the city with the latest wake-up time.

If you want sound sleep, think twice when choosing a job. The survey revealed programmers are most vulnerable to insomnia, followed by blue–collar workers, salespersons, consultants, online shop owners and online celebrities.

An important research finding was also released. For seniors who claim to have a sleep disorder, there is a marked likelihood in having depression. Sustained sleep problems will increase the probability of occurrence and recurrence of depression and worsen symptoms.

It also found sleep disorder is a dangerous cause of Alzheimer's disease. Enough sleep can protect the brain and lower the risk of having the disease.