A new study has found that one third of all women in Australia have experienced post-sex blues at some point, and the reason for it is not clear.
The period immediately after sex normally results in feelings of well-being, and mental and physical relaxation, but of the 200 young women surveyed, many felt the opposite, like feelings of melancholy, anxiety and tearfulness.
Queensland University of Technology Associate Professor Robert Schweitzer, who carried out the research, said 32.9 percent of respondents had experienced the phenomenon at some point.
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 post-coital dysphoria has been virtually silent but Internet searches reveal information on the subject is widely sought," the Courier Mail quoted him as saying.
"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," he stated.
But Schweitzer said his study had found only limited correlation between sexual abuse and post-coital dysphoria.
"Psychological distress was also found to be only modestly associated with post-coital dysphoria," he explained.
"This suggests other factors such as biological predisposition may be more important in understanding the phenomenon and identifying women at risk of experiencing post-coital dysphoria," he said.
The next stage of 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 post-coital dysphoria," he added.
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.