Diffuse brain injury (DBI) manifests as a spectrum of injuries and severity has been associated with several kinematic based metrics. However, influence of angular acceleration duration is often overlooked. This study provides a focused analysis of angular acceleration duration as a nonexclusive indicator of DBI severity. Functional deficits in rats, measured as time to reappearance of corneal and righting reflexes, were assessed following rotationally induced mild DBI. Subjects were exposed to mean angular acceleration durations of 2.0 ± 0.2 msec (mean ± standard deviation), and 3.0 ± 0.1 msec in short and long duration groups respectively. All other rotational kinematics were held constant. Functional deficits increased significantly (p<0.05) as a function of angular acceleration duration. Angular velocity was not sensitive to these functional deficits. Understanding the influence of duration independent of other influencing factors may highlight its role in the DBI mechanism and help identify appropriate DBI metrics.