The ranger wasn't a Jedi, he wasn't in tune with the Force in any way. It didn't take much effort for Jacen to put him out. Nor for him to sleep through the night. He didn't even realize what happened. There was no pain involved like he thought there might have been, no discomfort. Just darkness. Actual sleep. No dreams to haunt him for the first time in weeks.
Within seconds he was out, curled in his blankets and breathing evenly. No pain written in his face. Not even stirring once through the night. Jack didn't usually sleep, after Kira's death he found it was less satisfying and just gave up on it for more than a couple hours at a time. It was too bad he wasn't always able to have jedi-help when falling asleep, maybe he'd get more of it that way and not be so anxious anymore. But at least for now his mind was at ease, he didn't even hear them leave. The world had just seemed to melt away.