Sexsmonia – otherwise known as sleep sex – is a little known sleep disorder that causes you to do exactly what you’d expect: have sex, but when you’re dead asleep.

It falls into the same category as sleepwalking or sleep eating, except for the crucial difference in that it makes you engage in sexual activity without your consent, including fondling, masturbation, oral sex or full-blown intercourse.

Sexologist Dr Janet Hall tells us it can wreck havoc on your mental well-being and relationships.

“A person with sexsomnia may experience negative emotions such as shame, confusion, anger, denial, fear, guilt or frustration,” she says. “These negative emotions can lead to enourmous stress.”

What triggers an episode of sexsomnia differs from person to person: stress, alcohol, illicit drugs, sleep deprivation, primary sleep disorders or even sex itself. It occurs during the first few hours of sleep, when the cortex (the thinking, planning and awareness part of the brain) gets switched off, but the brain stem (the part responsible for basic urges like the drive to eat or have sex) is still working.

“By this stage, the sexsomniac is acting completely without inhibition,” says Dr Hall.

This obviously paves the way for extremely murky grounds; more than one person accused of rape has used sexsomnia in their defence, and more than one legitimate sexsomniac has been charged with sexual assault.

The most recent case was 26-year-old Mikael Halvarsson, a Swedish national who was sentenced to two years prison for sexually assaulting a woman sleeping beside him, but was acquitted in 2014 when the appeals court found him to be “in a state of sleepiness, unconscious of what was happening.”

Very little is known about this disorder, not least because people are extremely reluctant to report it. A 2010 study found that almost three times as many men experienced sexsomnia than women, but as their entire study consisted of people who had checked in to a sleep disorder clinic, researchers admitted their data might be skewed.

To shed some light on it, we spoke to Mark*, a 24-year-old Queensland bloke who’s been dealing with it since his teens.

PEDESTRIAN: How did you find out about your condition?

MARK: I first became aware of it when I was a teenager. One morning my long term partner at the time started to talk to me about my strange uncharacteristic behaviour while we were having sex the night before. I told her I had literally no memory of the interaction but didn’t think much of it until it began to happen frequently. I was aware that while growing up I had a tendency to sleep walk and sleep talk quite often and I think of these experiences as connected and rooted from the same place in my psyche.

PEDESTRIAN: What was your initial reaction?

MARK:  Initially I was a little embarrassed and wanted to keep the experiences secret but after learning more about sexsomnia I became more open about sharing with close friends. I was also disappointed by the fact that I missed out on the fun – All the work with no reward!

PEDESTRIAN: Can you describe what happens?

MARK: It’s hard to tell you exactly what happens because I’m unconscious during, so all the knowledge I have stems from information given to me. From what I understand it generally seems to happen very early morning around 2/3am, which I suspect is connected to the REM sleep cycle. I’m told I usually instigate with sexual advances and “dirty talk” although it’s as if I’m sleep talking because I’m unresponsive – the sex is is generally the same as if I were awake except I don’t acknowledge anything said to me and afterwards I’m straight back to sleep. Occasionally I will wake up during, but more often I won’t. It’s hard to say how often it will occur because there doesn’t seem to be a pattern other than it only happens with a partner or someone I’m very comfortable with. If I’m in a relationship, I would say roughly a few times a month.

PEDESTRIAN: Are there any triggers you’re aware of?

MARK: Like I mentioned earlier it only seems to only happen with someone I’m very comfortable with, as if my subconscious is aware of whom I’m sharing my bed with – so I would say that is my trigger. I also have found it’s more likely to happen if I’ve recently had sex, kind of similar to how if you’ve watched a scary film just before bed you’re more likely to have a nightmare.

PEDESTRIAN: Have you ever sought treatment for it?

MARK: I have spoken to my GP about it and he recommended that I could try some sleeping aids but it was not necessary unless it was really causing me or my partner stress. I have opted to avoid medication unless it begins to cause more severe problems. I decided to seek treatment options to educate myself on what was happening to me and how I could be controlled, for peace of mind.

PEDESTRIAN: How has this affected your relationship with partners?

MARK: Sometimes it’s had a very positive affect on my relationships for obvious reasons but it has also caused a little tension in previous relationships – mainly due to the loss of sleep for my partner. I remain reasonably unaffected but it can be difficult for my partner to face a full day of work after losing sleep because of our early morning escapades. Although I am reasonably easily deterred, it just takes annoyed groan and “not tonight” push… or maybe two.

To find out more about sleep disorders and sexsomnia, go to Sleep Disorders Australia or Australasian Sleep Association, or speak to your GP.

Photo: Sleeping Beauty.