Hello Yael
There are many possible causes of itchiness, so let’s start by removing a few from consideration. Firstly, clothing can cause itchiness, but that is not likely the case here as your student would be itchy all the time, not just while doing yoga. Allergies could also be a cause. Many people may be allergic to the yoga mat, blocks, cleaning agents, fragrances, etc., but again, any environmental causes would affect her regardless of the practice or postures. It is not unknown for exercise to cause itchiness as well, especially sweaty practices that leave salt on the skin after the sweat evaporates. Also, physical exertion can lead to releases of histamines, which can cause itchiness. Again, we can rule these out as yin is not a hot practice.
So, what are we left with? It is possible that relaxation and enhanced awareness can create itchiness. Firstly, by becoming aware of minor sensations we can inadvertently magnify them. For example, if I am aware of a slight sensation in my big toe, I may focus on it, which makes the sensation more obvious. Continued awareness may start to magnify the sensation even though there is nothing physically the matter. Hypervigiliance can turn mundane sensations into annoyingly powerful ones.
Stress can also play a role. One study found that “Stress is known to be an important aggravating factor in itch, but the precise mechanism by which brain activation results in stress-induced pruritus remains elusive.” (Pruritis means itchiness. See Kim HJ, Park JB, Lee JH, Kim IH. How stress triggers itch: a preliminary study of the mechanism of stress-induced pruritus using fMRI. Int J Dermatol. 2016 Apr;55(4):434-42. doi: 10.1111/ijd.12864. Epub 2015 Aug 14. PMID: 26276021.)
You asked if this was common. I would say no, but it is not unheard of. For your student, I would be curious to know where the itch was during Sphinx: was it in the targeted areas or somewhere else? Does she ever get this at other times? And, then, if it is a distraction, invite her to focus her awareness somewhere else, like the breath or a different targeted area.
I have written an
article on makyo, the strange sensations and even hallucinations that can arise during meditation and yoga practice. You may find it interesting to review as well.
Cheers
Bernie
