Yummy mummies have long sworn by breathing slowly to relax at their weekly yoga sessions.
Now scientists have found the idea of slow breathing is not mumbo jumbo, but actually works in the brain to create a sense of calm.
An experiment found mice became significantly more blissful after their breathing was slowed down.
While breathing exercises have been used for hundreds of years, and prescribed to panic attack victims, it was not known how they worked.
Researchers led by Stanford University discovered the answer by accident after knocking out neurons in mouse brains which control breathing.
A few days later, they noticed the animals, which were taking fewer fast, active breaths, were extraordinarily calm.
Lead author Dr Kevin Yackle, a Stanford graduate and faculty fellow at the University of California in San Francisco, said: ‘If you put them in a novel environment, which normally stimulates lots of sniffing and exploration, they would just sit around grooming themselves.’
This is the mouse equivalent of feeling very mellow indeed after a yoga class.
The scientists found around 175 neurons believed to be responsible deep in the brainstem, within a breathing centre also found in humans.
When certain neurons were wiped out, the mice took fewer rapid ‘active’ and faster ‘sniffing’ breaths, and more slow breaths associated with relaxation.
The investigators believe that these neurons ‘report’ to another part of the brainstem which can trigger anxiety and distress.
This area, also responsible for waking us up from sleep and keeping us alert, is likely to be the reason that people too feel calmer when taking slower breaths.
The study comes as ‘transformational breathing’ is set to be one of the biggest health trends of the year – dubbed the ‘new yoga’ by Vogue.
This involves deep and slow breaths and is claimed to induce a powerful state of calm, lower blood pressure, sharpen your thinking and even keep you looking and feeling young.
The theory is that fast, shallow breathing sends messages to the brain we are in ‘fight or flight’ survival mode and this spikes levels of stress hormones (cortisol and adrenaline), which can lead to chronic anxiety.
The Stanford study, published in the journal Science, states: ‘Slow, controlled breathing has been used for centuries to promote mental calming, and it is used clinically to suppress excessive arousal such as panic attacks.’
Similarly, the practice of pranayama — controlling breath in order to shift one’ s consciousness from an aroused or even frantic state to a more meditative one — is a core component of virtually all varieties of yoga.
Senior author Dr Mark Krasnow, said: ‘This study is intriguing because it provides a cellular and molecular understanding of how that might work.’
He added: ‘If something’s impairing or accelerating your breathing, you need to know right away. These 175 neurons, which tell the rest of the brain what’s going on, are absolutely critical.’
The area in the brain responsible for controlling breathing is the pre-Bötzinger complex, which regulates breathing, from sighing to gasping and yawning.
Scientists were aiming to alter mice’s breathing variations, after managing to knock out neurons allowing them to sigh, when they discovered the effect on their mood.