Altitude Plus Exertion (Including Associated Poor Sleep and Dehydration) Interact to Produce Cognitive Deficits

Outside Magazine summary here, PLOSOne study here. I strongly suspect that poor sleep at altitude is a (the?) major contributor to this, but in a multi-day climb like Kilimanjaro, I see no solution - wearing an O2 mask when you go to bed in your tent? Yeah, that sounds like the solution to restful sleep!