For what it's worth, I Don't think it's an extreme claim at all.
The potential for ill-effects from more extreme efforts in Meditation is starting to be documented by western scientists. A lot of adverse outcomes aren't only possible, but actually quite common.
I personally had ZERO prior mental health issues, but after 3-4 months of meditating 30-90 minutes everyday in addition to fairly intense mindfulness practice throughout the day, I started to experience a lot of issues: strange emotional outbursts disconnected from any memory or thought, anger management issues, tension headaches, depression, etc.
These ultimately only resolved by stopping meditation entirely for a long time and only carefully reintroducing it in smaller less frequent doses.
It's really not all sunshine and rainbows.
The Buddhists definitely know about this, but a lot of their writing is pretty impenetrable and interlaced with weird metaphysics. Here's some modern, secular words on the subject (from the admittedly controversial author Daniel Ingram):
https://www.mctb.org/mctb2/table-of-contents/part-iv-insight...
Here's a more traditional buddhist description of the same thing:
https://www.accesstoinsight.org/lib/authors/mahasi/progress....
I think a very small fraction of people actually meditate enough to get to that point. Meditating 90 minutes a day (plus the constant mindfulness practice) is pretty extreme by most people's standards (at least in US secular culture).
After that, for months, the head pressure / headaches would reappear and then they'd be relieved by me crying. Feeling the intense feelings and going away.
But... I really wasn't expecting any of that. I just wanted to be able to focus better and think more clearly. I didn't sign up for THIS. So I just let it go and fade. I didn't really want to accidentally screw my brain up. So, unfortunately, I haven't started a daily practice again since. It all did feel pretty cathartic though.
I've dabbled here and there with meditating again. When I do it with any real regularity though, the head pressure tends to come back.
Also, I'm not very fond of taking the traditional advice so literally. These sources focus solely on training new Buddhist monks, and most people doing secular practice just want some peace of mind while they continue their, productivity focused, western lifestyle.
We need to take these sources with a grain of salt and reorient our practice so that it cultivates more peace of mind without making us implode when the cultivated buddhist mindset creates a conflict with our western lifestyle
I've experienced intense emotional swings like you describe but not the pain or pressure. The emotional swings at least were something I was able to get through, eventually. They were strong for a while but stopped with continued practice. I'm definitely still more sensitive than I was before. I feel both positive and negative feelings more intensely, but hold onto them less.
This and linking MCTB (of all things) are the exact dangerous taking out of context I’m warning against. Daniel Ingram is a terrible resource, he should not be recommended
Here's where I think we differ: a lot of people in secular western culture are intensely put off by all the religious stuff that comes with Buddhism. The metaphysics and reincarnation stuff is, in my view, a reflection of the culture that Siddhartha Gautama grew up in and taught in, rather than a necessary part of eliminating suffering. I think that retelling these lessons in a way that's accessible to modern audiences is important. Some people simply will not accept something taught in the form of ancient mysticism. Should those people be denied insight just because they didn't grow up in India during the Iron Age?
I get that Ingram is polarizing. I'll add a link to Mahasi Sayadaw as well, but I just don't think he explains things in a way that's as clear to someone with my cultural background.
