This period is between 7:00 pm to 9:00 pm when the pericardium channels are "on duty". The pericardium is a double-walled sac that contains the heart and the roots of the great vessels, and its main purpose is to protect the cardiac muscle's normal activities. People should start preparing to enter sleep or to enter a light sleeping condition during this period.

The heart does not receive any direct bad particles from the body, so what does? It is the pericardium that receives any bad particles. When people start to notice that their heart is giving them problems, it is usually concluded that there are problems with the pericardium channels. When you suddenly start feeling your heart beating rapidly, it means that the pericardium has received some abnormalities. First, it might only be the heart beating a little fast, but problems would later follow deeper into the pericardium channels towards the heart. Traditional Chinese Medicine uses the principle of first treating/maintaining the regular activities of the internal vital organs (heart, liver, spleen, lungs, and kidneys) to the other organs (small intestine, gall, stomach, large intestine, bladder, and the three visceral cavities), therefore, once you understand how vital energy works then will you be able to treat related diseases.

The pericardium channels are happy to be "on duty", therefore, people should have a little bit of fun during this Xu Period.