Lack of sleep will affect your body performance because your body was not able to rest properly and the energy you have already extended has not been restored by proper hours of sleep.
the required number of hours for sleep must be observed in order for your body to regenerate the energy you have expended. Lack of sleep results to low energy which results to slow reflexes.
Notice that when you are very tired, you tend to bump into things even though you knew beforehand that there are obstacles in your way. This is a primary example of what lack of sleep will cause you. You also experience black outs, where your mental state shuts down but your body is still awake.
