Study of the Effects of Transcutaneous Auricular Vagus Nerve Stimulation Combined with Slow Breathing on Insomnia

Sleep latency, sleep efficiency, wake time after sleep onset, number of wake times after sleep onset, and total sleep time were used as the primary outcome measure in the sleep diary.

Heart rate variability(HRV) were analyzed to evaluate the mean peak interval (MeanRR) of the RR and three commonly used measures of autonomic nervous function: the root mean square sum of the difference between adjacent normal heartbeat intervals (RMSSD), the percentage of adjacent NN differences greater than 50ms in the total number of sinus heart beats (PNN 50%), and high frequency power (aHF).

Heartbeat evoked potential(HEP) is the electrical activity of the brain at a specific moment in the heart cycle, which is synchronized with the R wave of the heart's electrical signals and can be measured by recording the electrical activity of the brain at a specific point in time within the heartbeat cycle. HEP represents an electrophysiological marker of cortical processing of incoming cardiovascular information.

The Insomnia Severity Index (ISI) is utilized to assess the severity of insomnia and its impact on physical health, daily function, and quality of life. This scale includes seven items, with a total scoring range from 0 to 28. Higher scores denote more severe insomnia. The change in ISI score will be determined by subtracting the baseline score from the score at each subsequent time point.

The Pittsburgh Sleep Quality Index(PSQI) assessed the sleep quality of the participants in the last 1 month, which was composed of 19 self-rated items and 5 other rated items, in which the 19th self-rated items and 5 other rated items did not participate in the score. The 18 self-rated entries that participate in the scoring can be combined into seven sections. They were: sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disorders, hypnotic drug use and daytime dysfunction. Each part is scored from 0 to 3, and the cumulative score of each part is divided into PSQI total score, ranging from 0 to 21, and the higher the score, the worse the sleep quality

The Patient Health Questionnaire-9 (PHQ-9) encompasses nine items, each representing a different facet of depressive symptoms. The total score ranges from 0 to 27, with higher scores indicating more severe depressive symptoms. The change in PHQ-9 score will be determined by subtracting the baseline score from the score at each subsequent time point.

The Generalized Anxiety Disorder Scale (GAD-7) is used to assess the emotional state of patients. The Generalized Anxiety Disorder Scale (GAD-7) comprises seven items, with a total possible score ranging from 0 to 21. An elevated score suggests a more pronounced level of anxiety. The change in GAD-7 score will be determined by subtracting the baseline score from the score at each subsequent time point.

The Flinders Fatigue Scale(FFS) consists of seven entries that measure various fatigue characteristics (e.g., frequency, severity) experienced during the past two weeks. Six items were presented in Likert form, with responses ranging from 0(not at all) to 4(very serious). The total score is calculated by the sum of all the items. The total score of the scale ranges from 0 to 31 points, and the higher the score, the more serious the fatigue degree of patients.