This study adds to the existing body of literature demonstrating a relationship between circadian and seasonal variation and CV events. This study suggests that AF hospitalizations in the Bronx, New York, were significantly increased during the week after the spring daylight saving time transition compared with the yearly mean, whereas no increase in AF admissions were seen in the fall daylight saving time transition. Given that AF is associated with disturbed sleep patterns and stress, these findings might theoretically relate to a susceptible environmental-patient interaction during the spring daylight saving time transition that leads to higher risk for AF admission.

Patients, especially those at higher risk for AF, should be careful to maintain good sleep hygiene during the daylight saving time transitions.

These findings require validation in additional populations and physiological studies to understand the potential underlying mechanisms are needed to better understand the pathophysiology behind daylight saving time disturbances.

There are several limitations of the study and several aspects that are not clear. Where are these data derived from? It seems from Montefiore Medical Center, but it is not stated directly. It is important to validate these findings in additional hospital populations. This is an ideal study for the ACC registry-based data. Were all AF admissions included? How were elective admissions for cardioversion or ablation handled? Clearly these are not admitted on weekends. Also, it is possible that more procedures are done in the springtime, which confounds the observations. The ideal way to handle these issues would be to exclude elective admissions and just count AF admissions for uncontrolled rate/symptoms given the physiological plausibility. Why were Sundays excluded? Why were Fridays and Saturdays excluded from the main statistical comparison