The research and development of high altitude sleeping system: HASSSummaryVarious negative physiological effects of high altitude sleeping increase significantly above 12,000 feet. These effects include dehydration, hypothermia, susceptibility to respiratory tract infections, high-altitude sleep apnea, severe fatigue, and other conditions of varying severity. So far, technology has done little to solve these problems. Working at the Altitude Bioassay Laboratory at the University of Colorado Boulder, David de la Garza and I developed a high-altitude sleeping system called HASS. The HASS is a lightweight, inexpensive, easy-to-use device that can significantly reduce or even prevent many of the diseases mentioned above. This project presents the research, design, and field testing of a working prototype of HASS. What happens to the body when people breathe at higher altitudes? In the high mountains, the air is cold and completely dry. When inhaled air passes through the nose or mouth, it is warmed and moistened, drawing both heat and water from the body, and these are not recovered when exhaling. On the highest mountains where respiration is so greatly increased; this loss of heat and water cannot last very long. Dehydration exaggerates the impacts of hypothermia and hypoxia. —Dr. Charles Houston, MDWhy are these effects important and what can we do about them? As the previous quote attests, climbers (and other high-altitude adventurers) are at risk of hypothermia and hypoxia due to extreme cold, low humidity, and decreased air pressure. Additionally, they risk impairing their judgment and reflexes due to the effects of sleep apnea. All of these factors combined can greatly contribute to the danger associated with mountaineering or trekking. These symptoms are usually associated with sleep or become very acute during it. However, technology has done little to improve the sleeping environment for people living at altitude. Working at the Altitude Bioassay Laboratory at the University of Colorado Boulder, David de la Garza and I developed a high-altitude sleeping system called HASS. The HASS is a lightweight, inexpensive, easy-to-use device that can significantly reduce, or even prevent, many of the illnesses mentioned above (especially when sleeping above 12,000 feet). Our goal was to research, design, and field test a working prototype of HASS that would alleviate these conditions by keeping a sleeping climber's lungs comfortably warm and hydrated while increasing their respiratory rate throughout the night. How does HASS help with sleep? Is HASS designed to reduce the overall stress placed on the human body when sleeping at high altitudes.