It seemed relevant to share this dream with the rest of my Denali team as we discussed, over oat meal, the weirdness of altitude and how it had started to affect our sleep. They just starred at me with looks of deep concern. "I kinda wish you hadn't mentioned that," John "Johnnie Two Times" Harris commented. I decided not to mention my Phyllis Diller dream. Some of us could not sleep. Other's suffered broken sleep. We would have to adjust. It was part of living at altitude.
Sleep is essential in the physical and mentally demanding process of altitude climbing. I have known remarkably strong climbers to abandoned their quest after going several days unable to sleep. The human body goes through complicated changes as it adjusts to increasingly thinner air and sometimes it simply cannot manage the process efficiently. More often, we have rushed the process by ascending too quickly.
Sleep can also be troubled by factors unrelated to the altitude; anxiety, diet, hydration, or medications. For instance, many climbs require an approach through areas known for malaria. Some of the drugs taken to protect against this are also known to promote psychotropic dreams. On Kilimanjaro, my Brother in-law Ty woke from a horrible dream believing he was lying in a pool of blood with a knife in one hand. It so disturbed him that he discontinued the medication, preferring to take his chances with Malaria.
Far and away, the most prevalent sleep disorder associated with altitude is Chain Stokes Breathing. I did a climbing presentation recently at the local REI. Afterward I was approached by a man who had many questions about Chain Stokes breathing; whether I have ever suffered from it, how it may be dealt with effectively. His interest seemed more than academic, and I sensed his future in altitude climbing was in question.
I have experienced Chain Stokes breathing. It is quite common among altitude climbers. In short, you stop breathing for a period of 5 to 15 seconds while sleeping. Suddenly the alarms go off in your system and you wake gasping like a goldfish on a tabletop. This is further complicated by stifling claustrophobia as one is typically zipped up to his nose hairs in a thick mummy sack. The ensuing panic generates enough movement and profanity to wake one's tent mate, who in all fairness probably has it coming for waking you with his own bout of Chain Stokes twenty minutes prior. This may go on all night. ...and YOU took an unpaid leave of absence from work for this.
There are two mechanisms that regulate a person's breathing; The amount of carbon dioxide in the blood, and the level of oxygen in the blood. Think of them as bookends. When all is functioning properly you are at the far left with carbon dioxide levels determining your breathing cadence. It is the increased level of carbon dioxide in the blood during exertion that signals us to breath harder. But persistent increased breathing results in reduced carbon dioxide as we "blow off" levels consistent with normal respiratory functioning. This is not a problem in waking hours, when conscious breathing takes the helm. But at night we rely on the carbon dioxide level to keep us right.
The process breaks down at night as we breath hard to compensate for the thin air. This is turn starts to diminish the carbon dioxide level in our blood, signaling a diminished need to breath. Our bookends analogy would now see us moving away from the carbon dioxide end at an ever increasing rate as less breathing begets less carbon dioxide which in turn begets still less breathing. Finally a person's carbon dioxide level falls so low that breathing stops completely. One would think the other bookend, oxygen level in the blood, would gradually take over. It does not. Oxygen Level is on a union-sanctioned coffee break and has no intention of returning to work early. Five, ten, fifteen seconds pass before critically low oxygen levels in the blood trigger this far right bookend, resulting in desperate gasping which typically persists to the point of over-shooting in the opposite direction (too much oxygen in the blood), Oxygen Level goes back on break, and the cycle begins again.
Acetazolamide, also known as Diamox, is often used to combat Chain Stokes breathing. The excellent site BasecampMD.com http://www.basecampmd.com/expguide/diamox.shtml says This drug works by forcing the kidneys to excrete bicarbonate, the base form of carbon dioxide; this re-acidifies the blood, balancing the effects of the hyperventilation that occurs at altitude in an attempt to get oxygen. This re-acidification acts as a respiratory stimulant, particularly at night, reducing or eliminating the periodic breathing pattern common at altitude. Its net effect is to accelerate acclimatization.
I have never taken Diamox, preferring to deal with acclimatization through a balanced approach consisting of equal parts gradual ascent and self pity. But on Everest I will. It is simply too long a climb to suffer through poor rest, and too tall a climb to not stack the deck for solid acclimation. Color me Lance.