Welcome to the high country: Rocky Mountain National Park starts at the already-lofty elevation of 7,840 feet (at Beaver Meadows) and extends all the way up to 14,259 feet at the summit of Longs Peak.
Ever heard references to the “thin air” found in the mountains? That’s a nod to the reduced levels of oxygen saturation at high elevations: At 14,000 feet, only 61 percent of the oxygen you’d find at sea level is available.
Lower oxygen levels at elevation have several effects on the body: Breathing and heart rate increase as your body works harder to take in oxygen, and physical activity leaves you more winded than you’re used to at home.
You may have trouble sleeping at first. And some people experience a series of symptoms (headaches, fatigue, nausea) that add up to acute mountain sickness, or AMS. It's the most common type of altitude sickness and feels similar to having a hangover. You may not show symptoms until hours or a couple of days after you've been at elevation. Luckily, the body adapts to life at high elevation quickly, a process called acclimatization (if you move to a mountain town, for example, your body will produce extra red blood cells to carry more oxygen).
According to Web MD's website, "Altitude sickness can affect your lungs and brain. When this happens, symptoms include being confused, not being able to walk straight (ataxia), feeling faint, and having blue or gray lips or fingernails. When you breathe, you may hear a sound like a paper bag being crumpled. These symptoms mean the condition is severe." This is known as high altitude cerebral edema (HACE), in which fluid builds up within the brain. Should you experience these symptoms, seek treatment from a doctor.
Preventing Altitude Sickness
The best way to smooth your own transition on a trip to the high country is to take it slow: Spend a day or two between 5,000 and 7,000 feet before you go higher, and drink lots of water to prevent dehydration. Avoid alcohol and eat a high-carbohydrate diet. If possible, try to sleep at a lower elevation.
Treating Altitude Sickness
If you do develop AMS, the first thing to do is stop and descend to a lower elevation. A drop in 1,000 feet of elevation will help considerably. Ibuprofen and rest will help. Do not use sleeping pills or other depressants because they can suppress breathing.