I had a friend who had a massive panic attack on some medical train wreck that we got from the hospital in CA. It triggered him to have panic attacks after this for months, he had to go through all kinds of therapy to get rid of them. He would "forget" to breath while asleep sometimes and wake up suffocating. Obviously there were some personal factors involved, but a knock-out bowl of train wreck is what triggered it. Moral of the story, don't smoke a huge bowl of a strain you're not familiar with the first time maybe it's not a good idea for you.