What kind of Medicine is strong enough, and safe to use?

Patient: Hi, my brother recently got into a a severe car accident. I was told he had a .11 percent chance of living, however he made it out okay! Yay! Only problem is that since he had overheard his survival rate, he has had some form of PTSD, and a huge fear he might not live. His main problem now is that he cannot sleep at night at all. All of his dreams are terrible and he wakes up afraid. I love my brother, so my question is this: Is there any type of drug or medicine that we’d be able to get for my brother that would put him to sleep in no time? Something that will give him a full nights sleep no matter what. I’m worried his lack of sleep will only cause him more problems. We have tried the usual sleep-aids and even some various over the counter and prescription things to help him sleep but none of them work. Is there anything strong that will get him a good thorough night of sleep?

Symptoms: Sweating, little sleep, talking in sleep, not sleeping at all