Nearly four out of every 10 Chinese business people feel they were under serious stress despite their happiness improving each year, a recent survey has found.

The survey, conducted by Forbes China, found the happiness index of Chinese entrepreneurs increased from 7.8 in 2011 to 9 this year, an indicator that the majority of them are optimistic.

But the survey also discovered that nearly 40 percent were under pressure and one third felt stressed. Career, responsibility and social factors are major contributors to the mounting pressure they are under.