Transcutaneous auricular vagus nerve stimulation was conducted by transcutaneous electrical stimulation therapy instrument to the left earlobe. Stimulation parameters: frequency = 20/4 Hz; pulse width = 200 μs, twice a day, 30 minutes each time.

Non-motor symptoms such as sleep disorders were evaluated by Parkinson's disease sleep scale-2 (PDSS-2). PDSS-2 is an improved version of PDSS used to screen for common types of sleep disorders in Parkinson's disease patients. The minimum and maximum values of the non-motor part of the PDSS-2 Scale are 0 and 60. A higher score means a worse outcome.

Rapid-eye-movement Sleep Behavior Disorder Screening Questionnaire (RBDSQ) was used to assess the behavior disorder of multiple eye movement sleep. The minimum and maximum values of the non-motor part of the RBDSQ Scale are 0 and 13. A higher score means a worse outcome.

The Epworth Sleepiness Scale, also known as the Epworth Daytime Sleepiness Scale, was developed by Johns MW to assess excessive daytime sleepiness. This scale has clinical significance: it can provide a semi-objective assessment of sleepiness. Scoring more than 6 out of 24 indicates drowsiness, more than 11 indicates excessive sleepiness, and more than 16 indicates dangerous sleepiness.

The Hamilton Depression Rating Scale is the most widely used instrument for clinical assessment of depressive states, effectively reflecting the severity of the condition. The total score ranges from 0 to 76 points, with lower scores indicating milder symptoms and higher scores signifying more severe conditions.

The Hamilton Anxiety Scale is commonly used in clinical practice as a basis for diagnosing anxiety disorders and assessing their severity. The total score can be used to evaluate the severity of anxiety symptoms in patients with anxiety and depressive disorders, as well as to assess the effects of various pharmacological and psychological interventions. According to data provided by the Chinese Scale Collaborative Group: a total score ≥29 indicates possible severe anxiety; ≥21 confirms significant anxiety; ≥14 confirms the presence of anxiety; >7 suggests possible anxiety; and a score <7 indicates no anxiety symptoms.

The Montreal Cognitive Assessment is an evaluation tool used for rapid screening of patients with mild cognitive impairment. The assessed cognitive domains include attention and concentration, executive function, memory, language, visuospatial skills, abstract thinking, as well as calculation and orientation. The total score of the scale is 30 points, with test results indicating a normal value of ≥26 points.

The ΔHbO2 concentration in the brain cortex will be recorded in oxyhemoglobin.

5ml of the patient's elbow vein blood was collected and centrifuged after standing and stratified. The blood plasma was collected and frozen at - 20 ℃ for testing. Detection of changes in plasma ghrelin levels.

Using sleep logs to record participants' subjective sleep data, including subjective sleep quality scores，early morning refreshment scores, easy wake up scores, ease of falling asleep scores, and dreaming scores.

Using MI wristbands for objective sleep assessment, including deep sleep time scores，night waking up times, light sleep duration, and the REM sleep duration.