It most cases when one of my servitors have been knocked out, when the timer is done on what knocked them out they will wake up and resume following as usual.

Recently, an archon was knocked out from Garrotte (I assume, I was out at the time from the same thing) and I worded away when noticing that the archon was sleeping.

I was away for many hours and when the archon never came to me and I assumed that it was near dead and my attackers had killed it with a quick blow, but to see I sent the familiar to where the fight had happened and there was the archon still asleep.

Familiar woke the archon with simple wake command and archon was just fine afterwards.