Standing: Simple as it sounds, the human physiology depends on gravity. Seminal research in the 1930s showed that college athletes, when confined to bed for two weeks, lost months’ worth of muscle tone in their training. Standing up for only a few minutes a day keeps muscle tone intact. It also appears to aid in recovery from surgery, which is why patients are no longer advised to get constant bed rest in the hospital but encouraged instead to stand up and walk if they are able.
Walking: Although exercise delivers more benefit the harder and more frequently you exercise, the baseline for activity is walking. Research has shown that the widest gap in levels of physical activity, medically speaking, occurs between those who take zero exercise and those who get up off the sofa and do something, no matter how meager. Walking is now a regular practice in recovery from serious illnesses and surgery.
Rest: After heavy physical exertion, rest is necessary to replenish your muscles and restore internal balance—most people have no difficulty with this because they feel exhausted after heavy work or exercise. But the need for mental rest has only recently been taken seriously. If you equate mental rest with lethargy and dullness, that image is misleading. People who practice meditation, which among other things rests the mind, emerge with sharper alertness. Meditation doesn’t dull the mind or put the brain to sleep—there is actually increased brain activity (in alpha waves, for example, which are associated with creativity), resulting in a state previously unknown to neuroscience: restful alertness.
Sleep: Researchers still don’t know why we need to sleep at all, except that undeniably we do. The most recent theory is that sleep allows the brain to rid itself of built-up toxins during the day. These include, during the deepest stage of sleep, the removal of senile plaques that can cause Alzheimer’s disease. It is also during deep sleep that we consolidate what we have learned all day as short-term memories into long-term memories. Without these activities, our brain (as well as the rest of our body) can undergo damage done by lack of sleep and poor sleep.