I bet it's because you're so relaxed, and your body is being stimulated gently with pleasurable sensations constantly. So that increases the fire rate of all yo

I bet it's because you're so relaxed, and your body is being stimulated gently with pleasurable sensations constantly. So that increases the fire rate of all your sensory neurons, which are connected to other neurons. Then those fire, then they fire the ones they're connected to, etc.