Vision and breathing are, without question, the fastest and most obvious ways to control autonomic arousal. David Spiegel, associate chair of psychiatry at Stanford, and I are currently leading a study of breathing in which 125 participants have been wearing wrist monitors that measure breathing, sleep duration, heart rate variability and heart rate. So with vision and breathing, you are looking at physiological processes that are automatic but that we can also control. But you can control your diaphragm, which means you control your breathing, which means you control your heart rate, which means you control your alertness. Vision and breathing are essential as levers or entry points to autonomic arousal because they are available for conscious control at any point.