Schriefl C, et al. - In order to determine the influence of time of day on survival after out-of-hospital cardiac arrest (OHCA), researchers examined outcomes after OHCA between day and night. In addition, they investigated if variation exists in characteristics of pre-hospital advanced life support (ALS)-quality by the time of day. In this prospective cohort study, 1811 individuals [37% female; mean age: 67 ± 16 years] who suffered a non-traumatic OHCA in the city of Vienna between August 2013 and August 2015 and who received resuscitative efforts by EMS were included. Relative to previous studies, outcomes indicated no significant difference in sustained return of spontaneous circulation rates and 30-day survival with favorable neurological outcome after OHCA between day and night. The findings could be related to the observation that EMS personnel provided nearly the same high bystander CPR rates and identical ALS performance irrespective of time of the day return of spontaneous circulation.