When is meditation harmful?

I am planning to do two months of retreat under Pa Auk Sayadaw starting September 1. This will be an order of magnitude more intense than any retreat I've done so far, the longest a 2-week jhana retreat. Today I googled long meditation retreat harmful OR dangerous, and found Can Meditation be Bad for You?, by Mary Garden. She summarizes various research and anecdotal evidence showing that it can sometimes be bad. This evidence is far from conclusive, and it will be great when better research is conducted.

I am grateful to Mary for exploring under what conditions meditation can be harmful. This question is neglected in meditation communities. If you are interested in how and when meditation may be harmful, I direct you to her link. I have little disagreement with what she has to say, but I do have a comment on her conclusion.

She ends her article by saying that her life is "immeasurably richer" without meditation, that she "no longer regards the world as a place from which to escape or detach myself". She then quotes from the poem "Against Meditative Knowlege", by the Indian poet Rabindranath Tagore:

Those who wish to sit, shut their eyes and meditate to know if the world's true or lies, may do so. It's their choice. But I meanwhile with hungry eyes that can't be satisfied shall take a look at the world in broad daylight. (1896)

I think Mary, poet Tagore, and others may have searched for extraordinary experiences in meditation. For me, meditation is a practice that helps me look at the world in broad daylight. It helps uncover my hungry eyes, by giving me a better understanding of the fear that so often keeps those eyes closed.

Mary states that her morning swim relaxes her as effectively as meditation. For me, too, vigorous exercise is relaxing. But it is not as enjoyable. During vigorous exercise, I am haunted by anxious resistance. During meditation, I make the space to look the anxiety in the eye, and each time I do, I know it a little bit better.