Sleeping at Altitude
How to Handle Elevation
No matter how much dryland training I do before my ski trips to the Alps or U.S. West, I’m invariably exhausted during my first few days. It can’t be just the jet lag since I don’t have similar problems when I visit the U.K. Likewise, much to the surprise of my new friends, my alcohol intake is fairly constant regardless of my destination. Could the elevation be to blame?
The amount of oxygen in the air we breathe drops by 10 per cent at elevations of 1,500m and by as much as 25 per cent at 2,500m. This reduced oxygen has a profound effect on the quality of our sleep, which leads to daytime sleepiness. A restful sleep depends on spending sufficient time in the stages of REM and deep sleep, both of which are reduced as oxygen concentration falls.
How does this happen? The phenomenon of periodic breathing is felt to be the main reason. To compensate for a reduced oxygen level, our brain makes us breathe more quickly. The rapid breathing period is usually three to five deep breaths followed by 10 seconds of slow/shallow breathing. This cycle repeats itself multiple times each hour. While we may not be conscious of this happening at the time, this periodic breathing prevents us from spending enough time in deep sleep states.
The medication acetazolamide (Diamox) works by altering the body’s pH to compensate for our change in breathing pattern at elevation. Although technically a diuretic, acetazolamide works primarily by making the blood more acidic, which stimulates more-rapid breathing. This increased breathing is useful at high altitudes to compensate for the drop in oxygen. For this reason, acetazolamide can improve sleep at elevation and can also prevent more serious medical effects of altitude elevation. It’s best if taken one day prior to travel and then for the first two days at elevation to help with acclimatization. Since it acts as a mild diuretic, side effects can be reduced by staying well-hydrated.
This breathing phenomenon is made worse by taking sedatives such as alcohol or sleeping pills. The effect is even more pronounced if you already suffer from sleep apnea. If you sleep with a CPAP machine to help maintain consistent breathing patterns, it’s doubly important to have it when sleeping at elevation.
The bottom line is that the low oxygen at high altitude alters our breathing pattern, which reduces the quality of sleep. Since the effects of altitude on sleep tend to wear off after a few days of acclimatization, perhaps you could spend the first day of your trip at the spa or in the shops rather than bootpacking it off the top lift on your first run.
Dr. John Foote is an emergency room physician at Toronto’s Mount Sinai Hospital and a Devil’s Glen skier.altitude, altitude sickness