Abstract
Sleep at high altitude has always been considered to be of low quality. As a reason for this phenomenon, most researchers took the increased number of arousals accompanying the central apneas of hypoxia-induced periodic breathing (often wrongfully named Cheyne–Stokes breathing) into account. Climatic circumstances such as a very low air temperature, noise due to strong winds, and high humidity from snow or rain; different living environments with different nutrition; psychological peer pressure to reach the summit; and extreme exhaustion and increased sympathetic levels from the physical effort might add to the subjective feeling of sleeping poorly. From the end of the 19th century until the 1950s, measurements of sleep at altitude concentrated mostly on measuring respiratory parameters in field studies before then assessing neurophysiological signals in military hypobaric chambers. Since the1990s, data from polygraphy with neurophysiological channels at real altitude and from polysomnography in field studies have been available. These more recent data show that the quality of sleep—despite all inconveniences of sleeping at high altitude—is not as poor as previously thought. A satisfying amount of total sleep and, within this, satisfying percentages of rapid eye movement (REM) and delta sleep are reached despite the many arousals from hypoxia-induced periodic breathing. However, it is difficult to assess the impact of climatic influences on subjective sleep quality. Subjective sleep quality at high altitude might indeed be worse than in one’s own bed at home.