Background: Dome A (80°22′S, 77°22′E) has the highest ice peak in Antarctica, with an elevation of 4093m above sea level. It has a barometric pressure of 560-590 hpa, equivalent to about 5000m. Plenty of research at high altitude reported that hypoxia exposure is deleterious to sleep. This is the first study investigating sleep architecture and breathing disorders in healthy expeditioners from sea-level to high altitude at Dome A in Antarctica. Subjects and Methods: The study was carried out on ten healthy male volunteers (mean age 28.3±5.5 years) of the 31st Chinese Antarctic expedition to Dome A, who had provided written informed consent. Sleep was monitored using Embltta X100 portable polysomnography (PSG) at three conditions: (1) at Zhongshan Station (69°22′S, 76°22′E, sea level) before departure to Dome A; (2) at 4093m on the 13th-14th days after arriving at Dome A; (3) descent back at Zhongshan Station. The following channels were recorded: two electroencephalogram (EEG); two electro-oculogram left and right (EOG); chin and tibial electromyogram (EMG); thoracic and abdominal effort using inductance plethysmograghy sensors; oronasal flow was evaluated by an oxygen cannula and a pressure transducer; oxygen saturation was recorded during the night with a finger pulse oximeter. Results: The percentage of slow wave sleep (SWS) significantly reduced at Dome A (P<0.01).The percentage of REM (rapid eye movement) sleep remained in the normal range (15-25%) at both sea level and Dome A.There was no statistically significant difference in total sleep time, sleep latency and sleep efficiency. The respiratory disturbance index (RDI, /h) and apnea/hypopnea index (AHI, /h) substantially increased (P<0.001) under high altitude condition. The central apnea index (/h) was normal (<1/h) at sea level and rose progressively to 26.0±27.3 at Dome A (P<0.05). Apneas were almost exclusively of periodic breathing type appearing mostly during NREM (none rapid eye movement) sleep. The oxygen desaturation index greatly increased (P<0.001). The minimum SpO2 and mean SpO2 during sleep significantly fell at Dome A (P<0.001). Conclusion: Our field study reported novel data on sleep architecture, breathing patterns, and nocturnal oxygen saturation at Dome A (4093m) in Antarctica. High-altitude at Dome A reduced slow wave sleep and induced periodic breathing. Corresponding author: Chengli Xu (xuchengli@pumc.edu.cn)