The Centers for Disease Control has excellent advice for travelers to High Altitude areas in the mountains. They point out that Acute Mountain Sickness (AMS) is the most common form of altitude illness, “affecting 25% of all visitors sleeping above 8,000 ft (2,500 m) in Colorado.” Symptoms are similar to those of an alcohol hangover: headache is the main symptom, sometimes accompanied by fatigue, loss of appetite, nausea, and occasionally vomiting. They point out that supplemental oxygen at 2 L per minute relieves headache quickly and helps resolve Acute Mountain Sickness over hours, but it is rarely available. But it is available! Let us know if we can assist. Link here to the Centers for Disease Control and their Altitude Travel page.