In the late 1700s, German physician Anton Mesmer was enthralling Europe curing conditions from nervous disorders to blindness, or so he claimed.
According to Mesmer, an invisible magnetic fluid animated all living beings, and disturbances to it caused illness.
For so-called treatment.
Mesmer had his clientele form a chain around a contraption filled with water he allegedly magnetized.
Then, with waves of his hands, patients would fall into fits that would supposedly restore their health.
Some however, were skeptical, including King Louis XVI, who tasked renowned researchers with interrogating Mesmer's methods in 1784.
They conducted science's first-ever blind placebo trial, informing participants that they were receiving the magnetized treatment though they weren't, and vice versa.
The committee ultimately concluded that any positive outcomes weren't attributable to magnetism.
Instead, they were results of the participants' own imaginations, responding to suggestions about the treatment's effectiveness.
Mesmer disappeared, but the tantalizing takeaway remained.
And decades later, Scottish surgeon James Braid began utilizing aspects of mesmerism minus the magnetism.
Braid thought it induced a sleep-like state, so he called it hypnotism.
The practice today holds an entrancing place in popular fantasy.
But is there any truth to what it can accomplish?
Or is it just illusion?
While stage hypnosis has contributed to the conception that hypnotized people lose control over their actions, this doesn't seem accurate.
Whether or not they were hypnotized.
One study found that participants were just as likely to dip their hands into acid.
This might be because they felt motivated to take risks within the presumably safe confines of a psychology experiment.
Similarly, onstage participants might comply in the context of social pressures and fun, with perhaps some hypnosis at play.
But hypnosis used in medicine today looks different.
No props are necessary.
And while hypnosis was initially considered a trance-like state, it's now understood more as a set of procedures focused on suggestions.
No matter how informal.
Suggestions are natural features of doctor-patient interactions and we now know they can influence a patient's experience of their treatment.
Research-backed hypnosis sessions generally begin with a hypnotic induction, where a trained professional primes a patient for suggestions by drawing their attention to simple tasks like relaxing certain muscles.
Induction is supposed to help facilitate a more receptive mindset.
Then professionals make suggestions aimed at altering an aspect of the patient's perception, often describing something as though it will happen and be passively observed.
The session may close with a deinduction to ensure the patient is fully alert.
Most people seem moderately responsive to hypnotic suggestion, while small percentages are extremely responsive or unresponsive.
A person's hypnotizability doesn't tend to change much over time, though certain drugs and brain stimulation may increase it temporarily.
It's unclear what determines hypnotizability, but certain traits seem to be associated.
Highly hypnotizable people tend to be open-minded toward hypnosis, more prone to fantasy and likely to become absorbed in activities.
They also report more unusual perceptual and dissociative experiences overall.
When a hypnotic suggestion works, the effects can be considerable and traceable.
In some studies, researchers have prompted highly hypnotizable participants to perceive things that were otherwise absent.
In response, the hypnotized participant's brain activity has been shown to change in ways different from what's observed in imaginative processes, to instead more closely resemble actual perception.
For those it works with, hypnosis can be a helpful medical tool, though its scope is generally limited to psychiatry.
In one study, hypnotizable patients who received pain-reducing suggestions during surgery reported less pain and required fewer opioids afterwards.
Among patients with brain injuries, hypnosis has been observed to improve their working memory— that is, their ability to hold information like sequences of numbers for short periods.
This might be because the suggestions somehow ease cognitive deficits that are driven by the patient's own beliefs about their post-injury abilities.
And for certain things, including quitting smoking.
Hypnosis seems to be similarly effective to treatments like counseling and exercise.
But while hypnosis can help some people manage conditions like anxiety and depression, there's little evidence it can treat things like schizophrenia.
When hypnosis does help though, it's certainly no thanks to magnetized fluids, but rather the mesmerizing power of the mind.
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