Anxiety correlates with somatic symptoms and sleep status at high altitudes.

High altitude exposure results in many physical and psychological discomforts, with anxiety and sleep disturbances being the most common ones. This cross-sectional study was performed to explore the relationship between anxiety, somatic symptoms, and sleep status at high altitude. A sample of 426 young males between 18 and 24 years old ascended from low-level land to 3600 m, where they acclimated for 40 days, before ascending to 4400 m. Questionnaires including the Louise Lake Score (LLS, for diagnosis of acute mountain sickness [AMS]), the Self-rating Anxiety Scale (SAS), the Epworth Sleepiness Scale (ESS), and the Athens Insomnia Scale (AIS) were administered immediately before departure from 3600 m (40th day) and the day after arrival at 4400 m (20 days after the first data collection). Physiological parameters were also measured. We observed that 49 of 426 and 51 of 329 people were diagnosed with anxiety according to SAS at 3600 and 4400 m, respectively. Physical symptoms were more severe in subjects with anxiety, and the severity of anxiety was significantly positively correlated to the severity of insomnia and increased heart rate (HR). Overall, these data indicate that after 40 days acclimatization in 3600 m, anxious persons have more severe somatic symptoms. When ascending to higher altitudes, these individuals are more likely to develop AMS, show more severe symptoms, and are prone to insomnia and more serious daytime sleepiness. Insomnia and elevated HR are indicators of anxiety severity.