Napping for more than half an hour during the day was associated with a 90% increased risk of atrial fibrillation (AFib), but shorter naps were linked to a reduced risk, based on data from more than 20,000 individuals.
“Short daytime napping is a common, healthy habit, especially in Mediterranean countries,” Jesus Diaz-Gutierrez, MD, of Juan Ramon Jimenez University Hospital, Huelva, Spain, said in a presentation at the annual congress of the European Association of Preventive Cardiology (EAPC).
Judith Shidlowsky/Pixabay
Previous studies have shown a potential link between sleep patterns and AFib risk, but the association between specific duration of daytime naps and AFib risk has not been explored, he said.
Dr. Diaz-Gutierrez and colleagues used data from the University of Navarra Follow-up (SUN) Project, a prospective cohort of Spanish university graduates, to explore the possible link between naps and AFib. The study population included 20,348 individuals without AFib at baseline who were followed for a median of 13.8 years. The average age of participants at baseline was 38 years; 61% were women.
Daytime napping patterns were assessed at baseline, and participants were divided into nap groups of short nappers (defined as less than 30 minutes per day), and longer nappers (30 minutes or more per day), and those who reported no napping.
The researchers identified 131 incident cases of AFib during the follow-up period. Overall, the relative risk of incident AFib was significantly higher for the long nappers (adjusted hazard ratio 1.90) compared with short nappers in a multivariate analysis, while no significant risk appeared among non-nappers compared to short nappers (aHR 1.26).
The researchers then excluded the non-nappers in a secondary analysis to explore the impact of more specific daily nap duration on AFib risk. In a multivariate analysis, they found a 42% reduced risk of AF among those who napped for less than 15 minutes, and a 56% reduced risk for those who napped for 15-30 minutes, compared with those who napped for more than 30 minutes (aHR 0.56 and 0.42, respectively).
Potential explanations for the associations include the role of circadian rhythms, Dr. Diaz-Gutierrez said in a press release accompanying the presentation at the meeting. “Long daytime naps may disrupt the body’s internal clock (circadian rhythm), leading to shorter nighttime sleep, more nocturnal awakening, and reduced physical activity. In contrast, short daytime napping may improve circadian rhythm, lower blood pressure levels, and reduce stress.” More research is needed to validate the findings and the optimum nap duration, and whether a short nap is more advantageous than not napping in terms of AFib risk reduction, he said.
The study results suggest that naps of 15-30 minutes represent “a potential novel healthy lifestyle habit in the primary prevention of AFib,” Dr. Diaz-Gutierrez said in his presentation. However, the results also suggest that daily naps be limited to less than 30 minutes, he concluded.
Sleep habits may serve as red flag
“As we age, most if not all of us will develop sleep disturbances, such as insomnia, obstructive sleep apnea (OSA), and other sleep issues,” Lawrence S. Rosenthal, MD, of the University of Massachusetts, Worcester, said in an interview.
Therefore, “this study is near and dear to most people, and most would agree that poor sleeping habits affect our health.” In particular, OSA has been linked to AFib, although that was not measured in the current study, he added.
Dr. Rosenthal said he was not surprised by the current study findings. “It seems that a quick recharge of your ‘battery’ during the day is healthier than a long, deep sleep daytime nap,” he said. In addition, “Longer naps may be a marker of OSA,” he noted.
For clinicians, the take-home message of the current study is the need to consider underlying medical conditions in patients who regularly take long afternoon naps, and to consider these longer naps as a potential marker for AFib, said Dr. Rosenthal.
Looking ahead, a “deeper dive into the makeup of the populations studied” would be useful as a foundation for additional research, he said.
The SUN Project disclosed funding from the Spanish Government-Instituto de Salud Carlos III and the European Regional Development Fund (FEDER), the Navarra Regional Government, Plan Nacional Sobre Drogas, the University of Navarra, and the European Research Council. The researchers, and Dr. Rosenthal, had no financial conflicts to disclose.