I have been trying for that achievement and I can never catch him sleeping.

Thank you for the help.

There isn't a specific time, it just happens randomly while doing his quests. I haven't done his quests in a while, but I think he would sleep at least 2 or 3 times if I went through all the quests.

Thank you so much I have finally gotten it! I thought that it was a specific time and so I was always waiting to do his quests to try and find him sleeping.

I finally completed the map and was able to do his quests....then the very 2nd quest i ever did for him, he was asleep! I thought that it would take more than that, lol

I tend to find him sleeping 2-3 times out of all the quests. The nice part is you usually get a super rare item out of it.

It took me a couple of days before he finally went to sleep, not sure if that's normal or if I was just unlucky though. Best of luck to you!

Today i got the archivement without realizing it ...