Sleep is an essential part of your life. It is not only a form of rest, but a physiological function that helps your body to recharge and perform at its best the next day.
In TCM, sleep is part of the natural rhythm of Yin and Yang in the body. In the concept of Yin-Yang, Yin represents passive forces while Yang represents active forces. TCM classic The Spiritual Axis (Lingshu, 灵枢) uses the Yin-Yang concept to explain sleep in chapter 28. It is said that “when Yang is depleting and Yin is abundant, one’s eyes are closed. When Yin is depleting and Yang is predominant, one is awake.”
Sleep is also believed to be regulated by the cycle of Protective Qi (Wei Qi) and Nutritive Qi (Ying Qi). Protective Qi flows along Yang meridians for 25 rounds during the daytime and circulates through the Yin meridians for another 25 rounds at night. The cycle in the day enables the body to be active and awake, while the cycle at night enables the body to rest and recharge.
Sleep is a part of the Shen activities which function in the day and cease during the night to allow the Heart, Liver, Spleen, Lung and Kidney meridians to rest and recharge. You will be able to sleep well when the Shen is rooted and rested, but your sleep will be affected if the Shen is disturbed.
Ideal Time to Sleep
In TCM, Qi flows through 12 principal meridians within the body in a 24-hour cycle. When Qi flows through a specific principal meridian, it takes around 2 hours to vitalise and strengthen the organ system associated to that particular meridian before continuing to subsequent meridians.
The ideal time to sleep in accordance to the meridian clock is from 11pm to 5am. If your sleep is disturbed at a certain hour repeatedly, it is an indication that the paired organ system may require your attention.