Gottlob S, et al. - This study was undertaken to determine if infants born at 26–30 weeks’ gestation and having received their first routine hexavalent vaccination in the morning have a lower cardiorespiratory event rate (CER) after vaccination compared with those receiving it in the evening. For this analysis, 26 infants were randomized to an evening vs morning vaccination group in a pilot and main study with 10 and 16 participants, respectively. After vaccination, the body temperature rose in both groups. After vaccination, participants in the evening group slept longer. No difference between morning and evening vaccination in CER was identified, but after vaccination could confirm increased body temperatures and vaccination titers.