You have to give a speech in 10 minutes, the study subjects were told — so get ready.

A video camera recorded each step as they walked to the microphone, under bright lights, while "evaluators" in white lab coats held clipboards, ready to judge.

Sounds stressful? That's the point. 

This was part of a randomized, controlled clinical trial, designed to send hearts racing, blood pressure rising, and stress hormones coursing through veins, to test how patients with anxiety disorder handled the scenario after eight weeks of treatment.

The treatment wasn't a drug — it was mindfulness meditation.

"If we could show they were better able to cope, that would really be a big bonus for the treatment of anxiety disorders where people are sometimes overwhelmed by stressful experiences in their lives," said Dr. Elizabeth Hoge, lead author of the study published recently in Psychiatry Research.

The meditators didn't just feel better in the anxiety-inducing scenario, compared to the control group. 

The difference could be measured in their blood.

Amygdala in the brain

The amygdala, highlighted in orange in this illustration of the human brain, plays a key role in processing emotions. When it senses danger, it sends a distress signal that triggers our 'fight or flight' response. (Shutterstock)

Relaxation paradox

As we learn more about the dangers of chronic stress, calming down has arguably become a modern obsession, with mindfulness at the fore.

Of course, stress is part of life, and our bodies have an ancient response, to rise to the occasion. Faced with a threat, the brain sends signals to release stress hormones that trigger a cascade of changes throughout the body, from a racing heart to dilating pupils to slowed digestion.

This is quite helpful if you need to react quickly and, say, run from a lion. 

But the same cascade can be triggered by our own thoughts and worries — and when stress becomes chronic, it's linked to a higher risk of heart attack, stroke, obesity and other ills.

Mindfulness teaches to notice the intense feelings, without judgement, said Dr. Dzung Vo, a pediatrician who uses mindfulness to help struggling teens at B.C. Children's Hospital.

Trying to suppress the stress response doesn't work, he said.

"Paradoxically, the more we actually try to relax, the more we have something to achieve and to strive for, actually the harder it is to relax."

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More than 100 commuters join a meditation event in New York City's Flatiron Plaza in 2014, held by Headspace, a meditation app that makes an estimate $50-million per year. (Neilson Barnard/Getty Images)

Not a 'magical intervention'

But as mindfulness enjoys a pop-culture moment — touted in products from meditation apps to colouring books  — backlash has come, including from academics who warn the hype may be outpacing the evidence.

"I think there's something here," said Timothy Caulfield, Canada Research Chair in health, law and policy at the University of Alberta.

"But ... I think we need to be careful about the idea that mindfulness is good for everything, that it's some sort of magical intervention that will save the day."

2014 systemic review of mindfulness research, for example, found "moderate evidence" the practice helps with anxiety, depression and pain, but no evidence of effect on other things like mood, sleep and weight.

Caulfield also cautions about so-called "white-hat bias": because mindfulness seems both righteous and benign, he says the field hasn't faced enough scrutiny, even though it's become a billion-dollar industry.

"Just like 'big pharma,' there's big mindfulness."

What's needed, according to Caulfield and others, is more randomized, controlled clinical trials to know when mindfulness helps — and when it doesn't.

Cloudy skies

In the meditation study, participants were told to observe their emotions without judgement, 'like a cloud passing in the sky,' said Dr. Elizabeth Hoge of Georgetown University Medical Center. (Catherine Harrop/CBC)

'Like a cloud over the sky'

That's what Hoge and her colleagues set out to do with the clinical trial described above, aiming to test a technique called "Mindfulness-Based Stress Reduction" the same way they'd trial a drug.

MBSR was developed more than 30 years ago by Jon Kabat-Zinn at the University of Massachusetts Medical School, and is now used in hospitals in the U.S. and Canada.

Over eight weeks of classes and daily practice at home, the class learns breath awareness, a body scan, and gentle Hatha yoga, said Hoge.

"Pay attention to whatever arises in the mind," the participants heard, "with gentleness and non-judgement, and allow it to pass like a cloud over the sky."

The group that learned this meditation was compared to a control group. They took a different class with the same time commitment and homework, but learning to manage stress with diet, exercise and sleep, not meditation. 

meditation yoga

Mindfulness meditation was developed from millennia-old Buddhist techniques, but has gained new popularity for wellness and managing stress. (Getty Images/Hero Images)

After the training, the control group was actually more stressed, showing higher levels of stress hormone ACTH in their blood from the anxiety-inducing speech.

The meditators saw the opposite: ACTH dropped, as did pro-inflammatory cytokines — both markers of stress — suggesting the meditation had indeed made them more resilient.

"I treat patients with anxiety disorders with medication and psychotherapy, and I believe in both of those," said Hoge.

"But I think the thing that is special about meditation training is ... you're paying attention to your mind with kindness and gentleness. There's something that's very healing about that for some people."