Researchers at Chinese University said a study pointed to children more likely to have bipolar disorder, if their parents also have the condition.

Findings from the study carried out with the help of 10 hospitals in the Greater Bay Area showed that the risk doubled for children with one or both parents having bipolar disorder, compared with others whose parents don't have the condition.

The study also found that the risk of circadian dysfunction is four times higher for teenagers with one or both parents with bipolar disorder, and 7.5 times higher of having symptoms of social anxiety.

The researchers said this was because these teenagers have significantly lower-than-usual levels of melatonin, which helps with sleep.

The team said their findings form a roadmap of bipolar disorder symptoms which can help with treatment plans.

Professor Wing Yun-kwok, who heads the Department of Psychiatry at the university, said people with mental illnesses need to learn to live with them.

"I think mental illness or bipolar disorder is just like diabetes, blood hypertension, cancer. There's no difference. When you have too high blood glucose, that's diabetes. Too much blood pressure is blood hypertension. So you have too much swing in moods, actually it's bipolar," Wing said.