This is the period from 3:00 p.m. to 5:00 p.m. when the bladder channels are on duty. The bladder channel starts from the back of the foot and leads to the back of the calves, to the middle of both sides of the spinal column, and up to the brain, which is a long and large passage of vital energy that flows through.

For example, if one complains pains in the calves that could be a problem with the bladder channels, which is also called "Yang" deficiency. Yang deficiency means lack of vital energy to motivate your body. When there is pain at the back of the head, even deteriorating memory, it could be also because of bladders channels in disorder, which means the Yang deficiency in our bodies cannot propel the vital energy (Qi) and blood to the upper part of the body (head) to keep your brain nourished; therefore, the symptoms of deteriorating memory would show up. If one feels especially sleepy during the Shen Period, it would signify the deficiency of the Yang (Qi) energy.