Excessive daytime napping linked with elevated risk of heart rhythm disorder

Participants were divided into three groups according to their average daily napping duration at baseline: none, less than 30 minutes, and 30 minutes or more. Short daytime nappers were defined as those who snoozed for less than 30 minutes.

New atrial fibrillation diagnoses were initially self-reported and subsequently confirmed by an expert committee of cardiologists, who used a predefined protocol which included reviewing medical records. The risk of atrial fibrillation according to daytime napping duration was analysed after adjusting for the information collected in the questionnaire.

The average age of participants at baseline was 38 years and 61% were women. 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 (hazard ratio [HR] 1.90; 95% confidence interval [CI] 1.26–2.86). Meanwhile, compared with short nappers, risk was not elevated in those who avoided napping (HR 1.26; 95% CI 0.82–1.93).

The researchers conducted a second analysis to identify the nap duration associated with the lowest risk of atrial fibrillation. This analysis included those who reported regular napping and excluded participants who did not nap. Participants were divided into three categories according to their average daily napping duration at baseline: less than 15 minutes, 15 to 30 minutes, and more than 30 minutes. Compared with those who napped for more than 30 minutes per day, those who napped for less than 15 minutes had a 42% lower risk of developing atrial fibrillation (HR 0.58; 95% CI 0.35–0.95) while those who napped for 15 to 30 minutes had a 56% reduced risk (HR 0.44; 95% CI 0.27–0.72).

Dr. Diaz-Gutierrez said: “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. There are 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.”