“Under normal circumstances, the resolution phase of sexual activity, or period just after sex, elicits sensations of well-being, along with psychological and physical relaxation,” study author Robert Schweitzer of the Queensland Institute of Technology said in a statement. “However, individuals who experience postcoital dysphoria [sadness] may express their immediate feelings after sexual intercourse in terms of melancholy, tearfulness, anxiety, irritability or feeling of restlessness.”

Schweitzer said the cause of these feelings is unknown. One woman surveyed said that she feels “melancholy” after sex, but said those feelings are disconnected from her feelings of love and affection for her partner.