https://www.sae.org/publications/technical-papers/content/20..."This study investigated the driving characteristics of drivers when the system changes from autonomous driving to manual driving in the case of low driver alertness.
...
In the results, a significant difference was observed in the reaction time and the brake pedal force for brake pedal operation in the low alertness state, compared to the normal alertness state of the driver, and there were instances when the driver was unable to perform an adequate avoidance operation."