R.D.
What do you do when he wakes up? It is important to not turn on lights (or at least keep them low, like a low watt lamp, if you need to check diaper, etc.) because it makes his (and your) brain think it is daytime, releasing a chemical that helps your brain wake up.
My mom reminded me my baby is safe in his bed, so at six or seven months when he was still waking up, I would check on my son and make sure everything was okay, then let him 'cry it out' and he would get back to sleep on his own after ten to twenty minutes or so. It was difficult (heartwrenching) for me to hear him cry, but he must learn self reliance and to get back to sleep on his own. His doctor even told me to do that, and now he sleeps through. When he wakes up (I have heard him stir), he goes right back down pretty quickly now with little to no fussing.
If he is teething, that's another story. Do your best to comfort. When my boy is hurting (sick or whatever), I do get up with him and nurse him or give him Tylenol if he needs it.
Hope that helps!