The locals call it Mountain Sickness. I knew it by the name Altitude Sickness. I thought it comprised of prolonged headache, nausea, insomnia, and loss of appetite. What I didn't know is that if you do not suffer from any, or all, of the above you might still suffer from lack of energy. In other words, you'd be drained from all power to lift one foot and place it on the ground again. What I also didn't know is that many days after your successful ascent and descent to and from the summit you might suffer from a sickness akin to homesickness.
You may call it mountain sickness.