Background: The purpose of this study was to investigate the effectiveness and safety of transcutaneous vagus nerve stimulation (tVNS) to improve insomnia in the special environment of a plateau. Methods: This study was a single-center, single-blind, randomized controlled trial. A total of 100 patients with insomnia at high altitude were randomized into three groups receiving either transcutaneous vagus nerve stimulation intervention in the left ear tragus (treatment group), pseudo-stimulation intervention (sham group), or cognitive behavioral therapy for insomnia (CBTI group). The primary measure was the Pittsburgh Sleep Quality Index (PSQI) score. In addition, we assessed the patients’ objective sleep status with polysomnography and evaluated changes in the Insomnia Severity Index Scale (ISI) and Generalized Anxiety Disorder-7 (GAD-7) scores. We used one-way ANOVA and repeated-measures ANOVA for analysis. Results: Patients’ PSQI, ISI, and GAD-7 scale scores significantly decreased after 4 weeks of tVNS treatment and were greater than those of the control group. Polysomnographic data also demonstrated shortened sleep latency and longer deep sleep in the patients. Conclusion: tVNS is effective in improving sleep quality and reducing anxiety levels in high-altitude insomnia patients but should be confirmed in future adequate and prolonged trials to guide clinical promotion.

Firefighters have a greater prevalence of posttraumatic stress disorder (PTSD) because of their greater risk of exposure to traumatic events. Network analysis offers novel perspectives for understanding PTSD. However, most previous network analysis studies were cross-sectional and failed to reveal the dynamics and causality of PTSD symptoms. Therefore, this study aimed to elucidate the longitudinal development of and causal relationships among PTSD symptoms in firefighters. Two survey waves were conducted among 637 Chinese male firefighters: in April 2021 (baseline) and March 2023 (follow-up). We constructed two cross-sectional networks and one longitudinal cross-lagged panel network (CLPN) of PTSD symptoms. By comparing the two cross-sectional networks, we found that the central symptoms of PTSD changed over time, with central symptoms scattered across different dimensions at baseline and focused on the avoidance dimension at follow-up. The CLPN revealed causal relationships among PTSD symptoms and showed that irritability and nightmares significantly predicted other PTSD symptoms from baseline to follow-up. In summary, our study fills a gap in the longitudinal development of and causal relationships among PTSD symptoms in firefighters and provides potential targets for subsequent prevention and intervention.