Do You Catch Up on Lost Sleep with Daytime Napping? It May be Bad for Your Heart Health, Shows Study

Are you catching up on lost sleep at night with excessive daytime napping? Daytime napping longer than 30 minutes is associated with an increased likelihood of developing an abnormal heartbeat, a study showed.

According to the study, excessive daytime napping could be linked with the development of atrial fibrillation – the most common heart rhythm disorder called arrhythmia, when the heart beats too slowly, too fast or in an irregular way. While atrial fibrillation is generally not a life-threatening condition, people with this condition have a greater risk of stroke than others.

The risk, however, was not found to be elevated in those who avoided daytime naps. The research was presented at the ‘ESC Preventive Cardiology 2023’, a scientific congress of the European Society of Cardiology (ESC). It has not yet been published in any medical journal.

“Previous studies have suggested that sleep patterns may play a role in the development of atrial fibrillation, but as far as we know this was the first study to analyse the relationship between daytime napping and the risk of arrhythmia,” said author Dr Jesus Diaz-Gutierrez of Juan Ramon Jimenez University Hospital, Huelva, Spain.

How the study was conducted

The study used data from University of Navarra Follow-up (SUN) Project, a prospective cohort of Spanish university graduates. A total of 20,348 participants, free of atrial fibrillation at baseline, completed a questionnaire every two years. Information was obtained on sociodemographics (such as age, sex and working hours), medical conditions (high cholesterol, high blood pressure, diabetes, sleep apnoea, cardiovascular diseases including atrial fibrillation), lifestyle (napping, smoking, exercise, coffee intake, binge drinking, adherence to a Mediterranean diet, TV watching), height and weight.

Under the study, participants were divided into three categories: less than 15 minutes, 15 to 30 minutes, and more than 30 minutes. “Short daytime nappers were defined as those who snoozed for less than 30 minutes,” the author said.

The average age of participants at baseline was 38 years and 61 percent were women. The study stated that during a median follow-up of 13.8 years, 131 participants developed atrial fibrillation.

“Compared to short daytime nappers, those who snoozed for 30 minutes or more per day had a nearly doubled risk of developing atrial fibrillation. Meanwhile, compared with short nappers, the risk was not elevated in those who avoided napping,” the author added.

Optimal napping duration 15 to 30 minutes: Second study

The researchers conducted a second analysis to identify nap duration associated with the lowest risk of atrial fibrillation. “Compared with those who napped for more than 30 minutes per day, those who napped for less than 15 minutes had a 42 percent lower risk of developing atrial fibrillation while those who napped for 15 to 30 minutes had a 56 percent reduced risk,” said Dr Diaz-Gutierrez.

This analysis included those who reported regular napping and excluded participants who did not nap. According to the lead author, “the results suggest that the optimal napping duration is 15 to 30 minutes”. “Larger studies are needed to determine whether a short nap is preferable to not napping at all.”

Dr Diaz-Gutierrez said there were numerous potential explanations for the associations between napping and health. “For example, long daytime naps may disrupt the body’s internal clock (circadian rhythm), leading to shorter night-time sleep, more nocturnal awakening and reduced physical activity. In contrast, short daytime napping may improve circadian rhythm, lower blood pressure levels and reduce stress,” he said.