Sleep quality alterations in healthy workers at high altitude in Yushu area

During the period of reconstruction after Yushu Earthquake, a large number of sea-level or lowland workers ascended there and worked at altitudes between 3 750 m and 4 878 m which is a hypoxic environment. To investigate the sleep quality at that altitude, we performed two full polysomnographies （PSGs） in 10 volunteers, who were healthy male workers, aged 31 ：i：6.6, born and living at sea level, without experience of pre-altitude expo- sure. The assessment of subjective sleep quality was performed twice in each volunteer. The first investigations were carried out at sea level in Jinan city （pB=760 torr, 1 torr=133.322 4 Pa）. The second studies were performed at an altitude of 3 750 m （pB=416 tort） in Yushu Jiegu in the same 10 workers after they lived and worked at that alti- tude for 5 months. At sea level, workers presented a normal sleep structure and a higher oxygenation during sleep. However, as compared to sea-level sleep, at 3 750 m, workers had a shorter total sleep time （TST） （p 〈 0.001）, a longer stage 1 non-rapid eye movement （nREM） sleep （p 〈 0.05） and a shorter 3＋4 nREM and rapid eye movement （REM） sleep （p 〈 0.05） with a severe sleep hypoxemia （p 〈 0.01）. Our data suggested that sea-level workers revealed a disturbed sleep and a bad sleep quality with a significant sleep hypoxemia at altitude of 3 750 m. Strengthening the prevention and treatment are thereby sorely necessary.