FYI: my specialist, who has seen a lot of head injuries in his career, said sailing-related concussions are not uncommon (his wife actually sustained a sailing concussion). I think sailing is great, but I'm concerned about impacts from the boom (especially in a small craft like a laser or albacore) or from getting physically bounced around in windy or stormy weather. I haven't decided yet whether I'm going to give it up altogether, but I might - I believe I've had a few prior concussions - despite only one diagnosed one - and my recovery has taken a while (10 months so far, and despite some good progress, I'm not out of the woods yet).