The period immediately after sex normally results in feelings of wellbeing, and mental and physical relaxation.
But the study of more than 200 young women reveals many have experienced the reverse including feelings of melancholy, anxiety and tearfulness.
Queensland University of Technology Associate Professor Robert Schweitzer, who carried out the research, said 32.9 per cent of respondents had experienced the phenomenon at some point.
That was despite the sexual interaction being otherwise satisfactory.
Professor Schweitzer said the cause of such negative feelings was unknown but it was clear women wanted more information about the phenomenon.
"Research on the prevalence and causes of postcoital dysphoria has been virtually silent but internet searches reveal information on the subject is widely sought," he said.
"It has generally been thought that women who have experienced sexual abuse associate later sexual encounters with the trauma of the abuse along with sensations of shame, guilt, punishment and loss.
"This association is then purported to lead to sexual problems and the avoidance of sex."
But Prof Schweitzer said his study had found only limited correlation between sexual abuse and postcoital dysphoria.
"Psychological distress was also found to be only modestly associated with postcoital dysphoria," he said.
"This suggests other factors such as biological predisposition may be more important in understanding the phenomenon and identifying women at risk of experiencing postcoital dysphoria."
The next stage of Prof Schweitzer's research will look at emotional characteristics of women who experience post-sex blues.
"I want to look at how women view their 'sense of self'. Whether they are fragile or whether they are strong women, and investigate whether this leads to their postcoital dysphoria," he said.
The study, published in the latest International Journal of Sexual Health, was also authored by post-graduate psychology researcher Brian Bird and the University of Utah's Professor Donald Strassberg.
