Melbourne (PTI): The biological clock of humans is intricately linked with day and night. But if it falls out of sync, it can have serious psychological consequences, a new study has revealed.

Researchers at Swinburne University of Technology have studied the body clock or the circadian system and found that its rhythms can have profound effects on human mood, including triggering relapses in patients with bipolar disorder.

According to them, mood disorders such as bipolar disorder have long been linked to sleep problems, suggesting that the circadian system plays a role in these conditions.

"If you take seriously this idea that the body clock is part of a causal pathway to mood disorders, then a natural deduction is that monitoring clock function might provide early warning of relapse in vulnerable people," Greg Murray, the leader of the research team, said.

For their study, the researchers recruited 12 people with bipolar disorder and fitted them with wrist-worn devices designed to monitor their circadian system by measuring their physical activity throughout the day and night.

The study subjects were tracked for up to 12 months. In that time, one participant experienced a serious relapse that landed him in hospital.