Have you ever noticed that people rarely hum when they're overwhelmed? We hum while cooking, gardening, folding laundry or walking the dog. Most of us have heard that humming stimulates the vagus nerve, but the science may be even more interesting than that. Every time we hum, we change the way we breathe, shift our attention inward and provide the brain with a different pattern of sensory information. Could that be one reason it feels so calming?