Effects Of Chronic High-Altitude Hypoxia On Sleep And Mental Status In Workers From Lower Altitude Areas

Objective: To explore the effects of chronic hypoxia on subjective sleep and mental status in workers from lower altitude workng at a mean altitude of 4500 meters. Methods: 124 healthy workers who worked on the Qing-zang Railway at a mean altitude 4500m were selected as study group, and 117 subjects who worked in non high-altitude areas as control group. According to time exposed to the high-altitude hypoxia areas, the study group was divided into three subgroups: subgroup A working for less than 1 year, subgroup B working from 1 to 2 years, and subgroup C working for more than 2 years. They were all measured by Mult-Physio-Parameters Monitor, and evaluated with Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), and the Symptoms Checklist-90 (SCL-90). SPSS 10.0 statistical package was used for these analysis.Results: 1) Arterial Oxygen Saturations (SaO₂) of study group were lower than those of control group (P<0.001), and blood pressure (systolic blood pressure, diastolic blood pressure, and difference of pulse pressure) was higher than that of control group (P<0.01). Difference was found in SaO₂ among subgroups A, B and C. 2) There were negative correlations between the scores of PSQI, "sleep efficiency", "use of hypnotics", "sleep latency", "difficulty to full asleep" and SaO₂. Compared to controls, the study group had less sleep efficiency (P<0.01), and more hypnotics was used (P<0.001), while no significant difference was found on scores of ESS (P>0.05). In multi-comparisons among subgroups A, B and C, difference was found in scores of PSQI subscales "use of drugs for sleep" (P<0.05). The use of more hypnotics was found in subgroup B . 3) Correlations between SaO₂ and the SCL-90 subscales "Somatization", "Others" were...