A study from Guangzhou Medical University, China, has found that napping for more than an hour may be bad for your health.
Researchers looked at more than 20 studies that included a total of almost 314,000 people, about 40% of whom took naps. They found that those who napped for more than an hour a day had a 30% higher risk of death and a 34% higher risk of heart disease, compared to people who did not nap.
However, napping for more than an hour was only linked to a higher risk of death among people who slept more than six hours at night. And while naps of any length were linked to a 19% higher risk of death, naps of less than an hour were not linked to heart disease.
Study author Dr. Zhe Pan said that the results show that it’s safest to keep naps to under an hour, and if you don’t already nap, “There is no convincing evidence to start.” But he also said that shorter naps — less than 30 to 45 minutes — might improve heart health in people who don’t sleep enough at night.
A 2014 study from the University of Cambridge also found that, compared to people who didn’t nap, those who napped for less than an hour a day had a 14% higher risk of death, and people who napped for more than an hour had a 32% greater risk of dying — especially from lung disease. However, it wasn’t clear if napping led to illness, or if napping was evidence of having one.
Pan said that it’s not completely understood how napping affects the body, but that some studies have shown that long naps may lead to higher levels of inflammation, which is bad for the heart.
A 2019 study from Huazhong University of Science and Technology in Wuhan, China, also found that people who napped more than 90 minutes were at greater risk of having a stroke.