You say that you want him to "take some time off" but then mention that he is "often absent". This to me signals a much greater issue. I think if you were to remove him from your team it would be a huge mistake. We are people, not machines. Sometimes we go through hard times. You need to build a company that supports it's people during these difficult times not abandon them in their time of need. Talk to him and let him know you are there to support him.