Within a few hours of getting to a high altitude, people with AMS have nausea, shortness of breath, headaches, and trouble moving. All the delight you were feeling before things became terrible will be taken away by a general feeling of exhaustion. You can have trouble falling asleep, feeling lightheaded, and having a really bad headache. Additionally, you can become uncoordinated, have problems walking, and develop a tight chest. If the condition worsens to HAPE or HACE, you will experience confusion, shortness of breath while at rest, and most likely won't be able to move at all. AMS is not just present on hikes to the highest peaks or to the Everest Base Camp.