The Wu Period lasts from 11:00 a.m. to1:00 p.m and here is where the heart channels are on duty. The energy transforming point between the heaven and the earth usually happens at Zi Period and Wu Period, so, human body has to be aware of this point.

To an ordinary person, sleeping during the Zi period and the Wu period are very important. Sleeping at 11:00 p.m and taking a nap after lunch, even if it is just a short break with eyes closed, will be beneficial to a healthy body. Why? As the earth's energy is transferring at these two periods, it is the best in TCM philosophy that we'd better not stir its process because humans do not have the ability to disturb the earth's Chi (energy). What should we do then? Just take a rest, so as to meet all changes by remaining calm. Therefore sleeping during these two periods is beneficial to human body.