by Brian Walsh Ph.D.

There is a biorhythm operating 24/7 in our body known as the Basic Rest-Activity Cycle (BRAC). While some biological cycles last for many days, the BRAC oscillates consistently at between 90 and 120 minutes.

Rest portion: During this healing response portion of the cycle, there is more right hemispheric electrical activity, a spatial cognitive mode, and a settling down of the autonomic nervous system. Midway through the rest cycle is a trough of about twenty-minutes. This is when many cells of the brain that hold critical messenger molecules, such as adrenaline, are nearing empty. At this point, all the cells in the body are taking time out to replenish, rejuvenate, and rebalance. It is during this part of the cycle that people daydream, and can be most creative. Active portion: During this peak performance period of the cycle, there is greater electrical activity in the left hemisphere, a verbal cognitive mode, and the autonomic nervous system is in a phase of sympathetic predominance. This means that it is "open for business." Heightened physical activity, mental alertness, and energy means that logic, rationality, and a black and white approach are being exercised.

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