Women who suffer from the post-sex blues are wanted for a Queensland study.
Queensland University of Technology researcher Robert Schweitzer is trying to understand why some women experience feelings such as distress or nostalgia.
"The original findings are so counter-intuitive; everyone imagines sex as an enjoyable experience," he said in a statement.
"It's not easy to explain and the area is highly under-researched.
"Once we understand the experience we can start thinking about the role of clinicians in assisting people to understand and to address issues causing concern."
Professor Schweitzer's 2009 study of 200 women found that one in three experienced post-coital dysphoria, the experience of negative feelings following consensual sex.
His follow-up study involves confidential interviews.