The most successful way of improving human performance in high altitude areas with lowered oxygen levels is to add supplementary oxygen!
These are fairly common symptoms amongst individuals traveling to altitudes greater than 8,000 ft -- although this can occur at lower altitudes. One of the most unpleasant factors of going to a high altitude is difficulty sleeping well, because this effects how you feel the next day.
Click here for FAQ questions about altitude sickness
Click here to learn about a study on the use of oxygen rooms in high altitude areas.