Yes, you smoke all the time in rehab, nearly everybody does, its basically what you do between meetings, before sleep and during breakfast, lunch and dinner. The place is impossible to deal with without cigarettes. The food is usually good, you are taught stuff about drugs that you already know, talk with others about your experiences over and over again, go to AA/NA meetings, talk with your councelor and talk more about drugs. You'll find some people there that you can connect with. Basically you get time to get back on your feet to break the cycle of using and go home with a clear head.