Nodding off is common, like Anvilhead said, for all of the drugs you mentioned in the question. Suboxone can be helpful for those who are prescribed it in order to help them to drop the opiates. It is also addictive, extremely easy to abuse, and eventually requires a period of withdrawal to get off of. (Somehow my ex used to alternate abusing suboxone and opiates. To a lot of people, it doesn't seem to matter which drug is being used, so long as the craving to use is satisfied.) My BF just went through rehab in order to get off of it after several attempts at doing it himself. It wasn't pretty. The person you are asking about is using drugs. Unfortunately, it probably won't do you much good to accuse him of it. The best advice I've gotten here is to focus on YOU.