Jolt is a daemon which causes knocked-out guards to recover 1 KO damage, unless they are pinned. In addition to human guards, Jolt also affects rebooting drones.
Jolt is found in the Contingency Plan DLC.
Jolt is a relatively weak daemon; it only affects guards who are knocked out but not pinned. Regardless of Jolt, it is usually good to avoid knocking out guards where possible, and if you do knock them out then it is good to pin them. So, Jolt typically does nothing. If you have knocked out any guards, just try to pin them before triggering Jolt.
Jolt can occasionally be beneficial for the player, because of the bonus from Pheromone Filter. Jolt can also allow you to hack a drone again sooner.
If Jolt is triggered when shooting a guard with Overclocked Neural DART, then depending on the guard's KO resistance, Jolt can cause him to wake up immediately:
Clip from SuperStorm_8.
If the agent who fired the Overclocked Neural DART is seen by a guard who wakes up because of Jolt, then that guard shoots the agent immediately. This is because the Overclocked Neural DART triggers the daemon before the game checks whether any guards on overwatch should shoot the agent who attacked.
Clip from ZeekCannon.