Objective To understand the influence of Arctic environment on sleep quality of expeditioners. Methods Pittsburgh sleep quality index (PSQI) scale was used to investigate the sleep statuses of the 131 expeditioners for the China's 9^th Arctic research expedition before, during and after the expedition, and the sleep time point, morning rise time, sleep latency and actual sleep time were recorded. Results A total of 131 questionnaires were sent out, and 88 valid questionnaires were collected from 77 males and 11 females, aged 22-50 (48.1±17.9) years, including 18 crew members and 70 scientific research team members. During the expedition, the median morning rise time was 180 min earlier than that before the expedition, the sleep latency was longer than that before and 3 months after the expedition ([45.23±25.84] min vs[18.45±14.34] min and[19.50±12.57] min, both P<0.01), and the sleep time at night was shorter than that before and 3 months after the expedition ([6.83±2.24] h vs[8.36±1.45] h and[8.14±1.45] h, both P<0.01). According to the score of PSQI scale, the sleep quality was decreased, the sleep latency was prolonged, the sleep time was shortened, the sleep efficiency was decreased and the use of hypnotic drugs was increased during the expedition, with significant differences as compared with those before the expedition (all P<0.01). Conclusion Polar day and low temperature environment significantly affect the sleep rhythm of expeditioners, prolonging the sleep latency, shortening the sleep time and increasing the use of hypnotic drugs, which may affect the working state of expeditioners.