BEIJING - Chinese researchers have found that daytime naps lasting more than 60 minutes may raise the risk of heart disease and death.

Researchers from Guangzhou Medical University analyzed more than 313,000 participants from more than 20 studies to examine the link between napping and potential health risks. About 39 percent of participants took naps.

The results found that compared to those who did not nap, people who regularly napped for more than 60 minutes each day had a 34 percent higher chance of developing cardiovascular disease, and a 30 percent higher risk of all-cause death.

According to the study, naps, regardless of length, were linked with a 19 percent increased risk of death. The connection was more pronounced among women, with nappers seeing a 22 percent higher risk of death than non-nappers, and older participants, whose risk rose by 17 percent with naps.

The results suggest that shorter naps, especially those less than 45 minutes in length, might improve heart health in people who sleep insufficiently at night, said the researchers.

They said the reasons why snoozing affects the body are still uncertain, but some studies have suggested that long naps are linked with higher levels of inflammation, a risk factor for heart health. Other research also connected napping with high blood pressure, diabetes, and poor overall physical health.

The study has been published in the journal Sleep Medicine and presented at the European Society of Cardiology Congress 2020 digital conference.