0173 Concussion Risk in the National Football League is Highest During the Biological Afternoon and is Independent of the Mandated Concussion Protocol

Here, we developed a metric known as a human performance response curve (hPRC) to demonstrate advantages and disadvantages during the field-of-play in a NFL regular season that relies on the principles of the human circadian timing system For each team and game of a NFL regular season, we plotted risk for concussion with respect to each team's home biological time. Our hypothesis was that risk for concussion would be higher during predicted circadian "red zones" (biological afternoon) compared to optimal zones of circadian regulated alertness in the late morning and night games under the two-process model of sleep regulation. We also hypothesized that circadian regulation of risk for concussion would be independent of implementing a concussion assessment and return-to-play protocol. To support our hypotheses, we examined timestamps of concussions (based on each team’s biological (not actual) time) across the regular season pre-implementation of the NFL concussion protocol (2013) and post-implementation (2015). There were 140 documented concussions across the 2013 regular season prior to implementation of the NFL concussion protocol. In 2015, there were 218 documented concussions after implementation of the NFL concussion protocol. Despite implementation of the NFL concussion protocol, we discovered that the biological afternoon was a danger zone for concussions. In 2013, 75% of concussions (103/140) occurred during the biological afternoon. In 2015, this number increased to 82% (177/218) during the early biological afternoon. Moreover, time of day matters for concussion risk management. These data are sufficient and necessary for developing effective countermeasures to reduce risks for short-term and chronic head injuries (CTE) in professional football players. Not specified.