A new study is investigating how people feel immediately after sexual activity.
Although it's assumed that most people feel relaxed (and maybe tired) after sex, researchers have found there's a much wider range of responses to explore, including feelings of depression or sudden bouts of tearfulness.
"There are a wide range of responses in the period of time immediately following consensual sexual activity, known as the resolution phase," says Robert Schweitzer, a psychologist leading the research team at the Queensland University of Technology in Australia.
"For example, some people like to cuddle, others like to be alone and there are others, as we have found in previous research that experience what is described as post-sex blues."
So what exactly are the 'post-sex blues'?
Well, when people regularly feel anxious, tearful, melancholy, irritable, or restless after sex, it's called postcoital dysphoria.
This can last anywhere from 5 minutes to 2 hours, and can happen after any type of intercourse – including good and enjoyable sex.
"Overall, our previous research has shown postcoital dysphoria is prevalent in the general population and can occur in spite of an otherwise physiologically functional sexual experience," says Schweitzer.
But researchers don't know how common this phenomenon is, or who experiences it.
"There is anecdotal evidence that postcoital dysphoria is not uncommon in both men and women," he added.
"What this new study is seeking to do is survey men and women, heterosexual and homosexual to explore their experience during the recovery phase of sexual activity."
Right now, research on the prevalence and cause of postcoital depression is quite sparse, but a quick Google search shows it's an issue many people struggle with and want solutions for.
"One of the aims of this survey is to develop a scale that allows us to assess the resolution phase of the human sexual cycle and question the assumption that sex is solely excitement and pleasure," says Schweitzer.
"If we can better understand what is happening in the bedroom and the prevalence of post-sex blues, we can start looking at causes and possible solutions."
The researchers need your help to investigate the frequency and causes of postcoital depression.
If you're over 18 and have been sexually active, you can be part of this study here.