[audiometry]

Based on my own rock-bottom experience ( a very first-world rock-bottom problem ), I'd wouldn't identify them by some kind of 'objective measure of misery' litmus test. Instead I'd identify by saying, "a problem where my existing coping mechanisms no longer enable me to cope."

That's why some of these rock-bottom experiences can be great turns in life -- it forces you to do away with now-unhelpful coping strategies and find better ones.