My 31 Year Old Son, Can Not Stay Awake ,

My 31 year old son, can not stay awake , its as if he just passes out. He takes Suboxone. This is much worse than it ever was when he was using Heroin. Could it be a health issue such as narcolepsy or diabetes? He also says he hallucinates sometimes. If he were not a recovering addict, and he was just a normal person, would the passing out be symptoms of a condition?