Sensory Overload can cause fatigue, inability to fight infections, and poor digestion. It can contribute to high blood pressure, high cholesterol and painful muscle tension too. Here's why. Sympathetic and Para-Sympathetic Nervous Systems Humans have two nervous systems – the sympathetic and the para-sympathetic. We evolved primarily to use our calmer para-sympathetic system. That’s where we eat, hunt, work, sleep, make love, create shelter, ... Keep Reading >