if he has mixed methadone
with klonopin, he will be very drowsy, nodding off, eyes closing while talking, slurred speech, slow moving...he may seem fine while he is up and moving around, but when he sits to relax is when you will notice it the most...but if he is on a high dose of methadone, that alone MAY do this also...
but mixing methadone and benzodiazapines is extremely dangerous...i lost a close friend in december from this combination of drugs..