A META-ANALYSIS presented at the annual congress of the European Society of Cardiology suggests that excessively long naps may be detrimental to cardiovascular health in people who sleep more than 6 hours per night.

Whether it be a snooze after a copious Sunday lunch, a discreet 40 winks during lunch hour, or a long doze while on vacation, many of us love to nap, and having a siesta is the norm in many parts of the world.

However, it has long been known that sleeping too much can have negative consequences.

In particular, scientific studies have demonstrated that it can be harmful to cardio-vascular health.

But why is excessive sleeping damaging to health? And if that is the case, how are people supposed to catch up on lost sleep?

This week, a group of Chinese researchers, who set out to explore these questions in a large-scale meta-analysis, presented their findings at the annual congress of the European Society of Cardiology.

In the light of their analysis, which examined data from some 20 previous studies involving a total of 313,651 participants, the researchers concluded that naps of more than 60 minutes are associated with a 34% higher probability of cardiovascular disease, as well as a 30% increased risk of death from all causes.

However, they also discovered that these negative findings do not apply to people who sleep for less than six hours per night.

"The results suggest that shorter naps (especially those less than 30 to 45 minutes) might improve heart health in people who sleep insufficiently at night," points out Dr. Zhe Pan of Guangzhou Medical University, China, who led the study.

Doubt remains as to why excessive sleeping may have a negative impact on health.

Some studies have linked long naps to higher levels of inflammation that can affect heart health and reduce longevity.

Other research has associated them with hypertension, diabetes and generally poor physical health.

"If you want to take a siesta, our study indicates it's safest to keep it under an hour.

"For those of us not in the habit of a daytime slumber, there is no convincing evidence to start," conclude the authors of the study.