Some advanced yogis can control their bodies in extraordinary ways, many of which are mediated by the nervous system. Scientists have monitored yogis who could induce unusual heart rhythms, generate specific brain-wave patterns, and, using a meditation technique, raise the temperature of their hands by 15 degrees Fahrenheit. If they can use yoga to do that, perhaps you could learn to improve blood flow to your pelvis if you're trying to get pregnant or induce relaxation when you're having trouble falling asleep.
Do you ever notice yourself holding the telephone or a steering wheel with a death grip or scrunching your face when staring at a computer screen? These unconscious habits can lead to chronic tension, muscle fatigue, and soreness in the wrists, arms, shoulders, neck, and face, which can increase stress and worsen your mood. As you practice yoga, you begin to notice where you hold tension: It might be in your tongue, your eyes, or the muscles of your face and neck. If you simply tune in, you may be able to release some tension in the tongue and eyes. With bigger muscles like the quadriceps, trapezius, and buttocks, it may take years of practice to learn how to relax them.
Stimulation is good, but too much of it taxes the nervous system. Yoga can provide relief from the hustle and bustle of modern life. Restorative asana, yoga nidra (a form of guided relaxation), Savasana, pranayama, and meditation encourage pratyahara, a turning inward of the senses, which provides downtime for the nervous system. Another by-product of a regular yoga practice, studies suggest, is better sleep—which means you'll be less tired and stressed and less likely to have accidents.
Yoga can help you make changes in your life. In fact, that might be its greatest strength. Tapas, the Sanskrit word for "heat," is the fire, the discipline that fuels yoga practice and that regular practice builds. The tapas you develop can be extended to the rest of your life to overcome inertia and change dysfunctional habits. You may find that without making a particular effort to change things, you start to eat better, exercise more, or finally quit smoking after years of failed attempts.