Stimulating the vagus nerve increases its activity, resulting in a drop in heart rate, an increase in HRV (heart rate variability) within 3–4 weeks, and the activation of the parasympathetic nervous system. This makes you calmer, less stressed, less anxious, and results in better sleep.
Some factors could affect your results, however. If your HRV is under 50, it is too low, meaning you can have issues with your gut, ability to relax, blood pressure, and several other things. If it is around 80, it is very good. And 100, of course, means it’s perfect.