It's easy to think of hypnotherapy in the context of a comedy hypnosis show, in that it's some kind of magic trick designed to make 'unsuspecting' contestants do crazy things.
But take the practice away from the limelight, and it's actually used for a range of different things, including medical, psychological and dental treatments. It's even been linked to assisting people shed unwanted habits, like smoking, and promoting better sleep.
But does it actually work, or do people just like to think it does?
Is hypnosis real?
"Absolutely," Amanda Barnier, professor at Macquarie University's Department of Cognitive Science, told HuffPost Australia.
"Hypnosis has a really old history -- at least as old as psychology, if not older.
"In the past it has been used to conduct surgeries, amputations and assist people with really severe pain. It actually has a really nice, long, experimental and clinical history and is very scientific."
So, not just used to make people cluck like chickens, then.
"What you see sometimes on those shows... I really think it does clinical hypnosis a disservice," Barnier said. "It's making people and hypnosis look ridiculous when in fact it's a really powerful tool for clinicians to have in their toolkit.
"I've sat with thousands of people in our hypnosis laboratory and it's just me and them having really compelling experiences. And they are complex."
What can hypnosis be used for?
According to Barnier, hypnosis can be used to provide effective relief for a number of psychological and physical symptoms.
In a piece for The Conversation, she wrote: "Psychologists and medical practitioners have used hypnosis to help treat conditions including anxiety, depression, habit disorders, trauma, and acute and chronic pain.
"Indeed, economic and meta-analyses show that hypnotic treatments can have long-lasting effects and cost half as much as some traditional treatments."
Looking at habit disorders in particular, Barnier said hypnosis could assist people control their eating, quit smoking or even stop biting their fingernails.
"Not everybody can benefit from it, and it's usually best combined with other techniques," Barnier said. "But in the hands of a skillful therapist, it can be a powerful tool, and it can -- and has -- helped many, many people."
Can I be hypnotised?
Whether or not hypnotherapy would work for you (and how effective it would be) really depends on how hypnotisable you are.
"People differ in their hypnotic ability. Not everybody can experience hypnosis," Barnier told HuffPost Australia.
"Not everyone is going to get the same effects out of it."
According to Barnier, around ten to 15 percent of the population are "highly hypnotisable", meaning they respond to nearly all hypnotic suggestions, and around the same percent are "low hypnotisable" and rarely respond to hypnotic suggestions, if at all.
The rest of us sit somewhere in the middle.
"That medium level is where people can respond to many suggestions, but not necessarily all of them," Barnier said.
Suggestions themselves differ in difficulty, with Barnier noting more complex suggestions "are ones where you invite people to experience the world in a really different way, so to see things or hear things or taste things aren't there. These are harder to experience."
An easier suggestion, she said, would be something like your arm feeling heavier and having your hands pulled apart by magnets.
How does hypnosis work?
While research has shown hypnosis can lead to improvements in both health and lifestyle, how it actually does this is less clear.
"One of the scientific enigmas that remains for hypnosis is that its mechanism for pain reduction isn't clear," neuroscientist Marjorie Woollacott wrote for HuffPost in 2016.
"Unlike chemical anesthetics, which universally act on a specific part of the brain, hypnosis has differing physiological effects on various individuals.
The fact we are still discussing it as scientists doesn't invalidate it.Amanda Barnier
"One study found that in the same procedure, hypnosis caused pain-reducing physiological changes for some subjects in the anterior cingulate cortex (the brain's decision-making center) and for others in the somatosensory cortex (perception of touch).
"This suggests that with hypnosis, the individual's own mind has the ability to choose where in the brain the experience of pain will be blocked -- either a decision making center or a sensory center."
But the fact we're still learning about hypnosis shouldn't mean we doubt its effectiveness, Barnier argues.
"The fact we are still discussing it as scientists doesn't invalidate it," she said.
"In the same way memory researchers are finding out more about how our memory works, it doesn't mean memory isn't real."Suggest a correction