There’s a lot of woo around meditation, unfortunately. Even the purportedly scientific studies fall short of the standard in the majority of cases . It’s little wonder there’s no consensus from health organisations at this stage. The minority of studies that are peer-reviewed and include the proper controls however point to a range of health benefits. These include:
improvements in mood stress resilience attentional control memory improvements physiological improvements slowing of aging (!?)
Paraphrasing from the mindfulness section of the Wikipedia Meditation Research page , which itself links to all of the relevant studies:
The structure of the brain itself is changed in as little as 8 weeks of continued practice, with different types of meditation causing different changes. Focused attention vs open monitoring approaches, for example.
I find it astonishing that the act of thinking, reflecting, can lead to “fixes” in our biological machinery. Remedying many of our daily frustrations by effectively maintaining our brains through thought itself.
Limits and risks
Despite these remarkable findings, it’s entirely possible for meditation to go wrong for some people. Unpleasant experiences can occur from delving deeply into issues around one’s past or self. This is actually common enough to be an expected part of certain Buddhist traditions . Then there are risks for people who have problems around negative rumination or emerging crises. Meditation may worsen things in those cases.
For our purposes I’d suggest keeping it light, with the goal being to improve focus and stress resilience. If you want to go deeper an experienced practitioner should guide and assist in case any potential negative effects emerge. I may try to put together a few ideas for meditation techniques for our purposes in the future, but for now basic mindfulness techniques will suffice.
Looking into whether it was possible to meditate too much, or not enough, I found the following quote:
Other studies on expert meditators – that is, subjects with at least 40,000 hours of mindfulness practice under their belt – discovered that their resting brain looks similar, when scanned, to the way a normal person’s does when he or she is meditating. At this level of expertise, the pre-frontal cortex is no longer bigger than expected. In fact, its size and activity start to decrease again, says Taren. “It’s as if that way of thinking has becomes the default, it is automatic – it doesn’t require any concentration.” 
I worked 40,000 hours out to be approximately 55 years of 2-hour a day meditation, or 5000 8-hour sessions, or 14 years of continuous working-hours meditation. Not something most of us have experience with, then, it’s safe to say.
The true minimum required for permanent brain change is probably still to be studied, but the fact that the changes can be made permanent at all is eye-opening.
That there is a cost-free practice that anyone can access, at any time, to improve their cognitive abilities, potentially for the rest of their lives, is nearly unbelievable in this age of high-materialism. If this could be sold as a pill or marketed by some pharmaceutical, people would be lining up down the street.
Perhaps it is still the spiritual connotations holding more people back from engaging with it, a lack of clinical guidance, as the article above goes on to suggest.
In either case it’s one to watch as the studies keep rolling in. It does little harm in small amounts, at zero cost, with a potentially huge upside… I think I’ll stick to the routine until clinical advice says otherwise!
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 […] seven stages of purification mentioned in Theravāda Buddhism, or possible “unwholesome or frightening visions” mentioned in a practical manual on vipassanā meditation. Source