Thanks, Ira. So far I've found a number of related lay articles by the Australian doctor, but haven't yet located her actual study. I'll look some more.it does seem as though they characterize the nightmares as one aspect of PTSD, which also is common among heart surgery survivors. As I mentioned, I have had occasional mild flashbacks to the hospital but nothing disturbing and I treat them more as a matter of intellectual curiosity than anything else.You might be interested in reading a book by Oliver Sacks entitled "Hallucinations." He provides anecdotal descriptions of hallucinatory and dreamlike experiences of patients with various medical conditions including migraine, Parkinson's, etc., but nothing directly related to heart surgery. I found it interesting for a number of reasons including the possibility of making associations that might be applicable to open heart surgery patients. I would have loved to discuss my experiences with Dr. Sacks but, alas, he died three years before my open heart surgery in 2018.