Your brain on yoga nidra

Credit to FLY:D from Unspash

There’s a perception that immunology is really complicated. When I worked at Nature, copy editors avoided covering the immunology journal because of this apparent complexity; the fear of all the crazy acronyms and ridiculous number of cell types and subtypes. Ed Yong even made a joke about it in his famous article from the start of the pandemic.

So ok, the immune system is complicated and not as predictable or systematic as we would like, but my god, have you met neuroscience?

You’re probably wondering where I’m going with this and possibly even pleading with me to get to the point. Apologies. I know I’m generally very concise, so I felt like indulging in a tangent today.

I did a deep dive into the neuroscience of yoga nidra

Don’t be impressed. There wasn’t that much of it. But some interesting things did come up.

Yoga nidra may lead to altered states of consciousness

The first study to (properly) look into what happens to the brain in yoga nidra was back in 1999, using PET imaging (positron emission tomography, which can produce 3D images of the brain and other body parts). They observed changes in which parts of the brain were active during ‘normal’ consciousness and yoga nidra, with the latter characterised by loss of conscious control and the experience of rich imagination.

A follow-up study by the same researchers (who are clearly into this topic as they are the main ones to publish studies) found that during yoga nidra, there is increased blood flow to the parts of the brain that are associated with sensory imaging and memory, and reduced blood flow to the parts of the brain associated with executive function (eg planning, time management and control of inhibitions).

More recently, a small study (just 6 participants) showed similar results, with participants reporting reduced rational thinking and loss of conscious control (although worth noting that they had been practicing yoga nidra for 2 hours! 2 hours!!!! You’ve got to wonder whether just lying down for 2 hours and listening to music would make you feel the same way. Sometimes I feel that way after a massage).

Different parts of the practice activate different parts of the brain

Which you’d expect as each part of the practice invites participants to do some fairly different things. For instance:

  • Rotation of awareness activates the parts of the brain associated with spatial awareness and movement coordination (parietal lobe), as we are invited to feel different parts of our bodies
  • Images activates the part of the brain that is associated with visual processing (occipital lobe), which again makes sense because we are invited to recall or recreate images, people, places and so on
  • Invitations to feel eg feel joy, activates (unsurprisingly) the part of the brain that is thought to process emotions (superior temporal lobe)

Why look at the neuroscience of yoga nidra?

Other than the fact that it’s interesting to understand the science, the catalyst for me was watching the recent Netflix documentary by Michael Pollan on psychedelics (if you haven’t seen it already, I recommend it).

The documentary highlights recent research showing the mental health benefits of psychedelics, for instance in depression and OCD. I honestly don’t know how strong or biased this research is, but it got me wondering whether there are any parallels (obviously to a much much smaller extent in yoga nidra) which may explain the mental health benefits of yoga nidra beyond stress reduction and parasympathetic activation (eg 1, 2).

I have no answers, only questions.

What do you think?

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