Career Help and Advice

I would recommend that you do so jointly with other co-workers that are in agreement. You can coach this in terms of both concern for fellow employee - and also as a performance, and thus productivity, issue. And you should immediately start (after squaring with co-workers) 1) documenting behavior and instances (preferably through recordings), and 2) research what chain of command and HR options are there within the organization that you can take your concerns to when you are prepared.

I would be quite leery about confronting an issue such as this (except perhaps in the most casual and offhand manner. "You feeling OK today, Jim?".) on a personal level. IMO - the chances for an 'intervention', or something similar, going well at your level ... Seem pretty slim. This person's superiors probably need to be in the loop.