Sleep is essential to maintaining health, the ancient Chinese believe. TCM has a number of rules that can help bring the right sort of rest for the troubled at night.

Ancient kings and emperors spent their entire lives searching for the secret of longevity but the secret might just have lain in their pillows. Good sleep can help regulate energy flows and improve health. To enjoy good sleep, our TCM doctor suggests no late suppers, no late heavy physical exercise, don't go over things in your mind and don't lie on your left-hand side.

The ancient Chinese attached great importance to the role sleep plays in maintaining health. A Chinese maxim says that replenishing health with medicine is not as good as replenishing health with diet, but that replenishing health with sleep is the best treatment of all.

An important measure of health in TCM is having energy and healthy blood. TCM believes that the body has wondrous abilities to recover and heal itself as long as there is sufficient energy and blood circulating properly.

Our daily activities use up energy and blood and these can be restored with sleep. Good sleep not only helps us maintain our energy throughout the day but also helps us recover from sickness sooner. Those who sleep badly are prone to falling ill more easily.

Ensuring that you have seven to eight hours of good sleep every night should be your target, according to Dr Yuan Canxing, chief physician of Neurology Department of Longhua Hospital attached to Shanghai University of TCM. But for some people, this is difficult.

Sleep is when yin (cold) and yang (hot) energies change and shift inside the body, according to the "Huangdi Neijing" (Medical Classic of Yellow Emperor), one of the fundamental classics of TCM. When yang energy enters yin, people sleep; when yang energy exits yin, people wake. And the heart which governs the spirit (intelligence and thinking) is the organ in charge of the process.

"A healthy heart relies on sufficient blood nourishment and people who have sleep problems usually suffer from inadequacies of the heart," says Dr Yuan. "For most people, this is caused by an unhealthy lifestyle."

Staying up late too often and suffering constant mental stress can lead to latent heart-blood problems. Bad moods like depression and irritation lead to the stagnation of liver energy and prevent energy and blood flowing to heart.

Eating rich food just before going to bed will rob the heart of blood and energy for digestion. And indulging in heavy physical exercise late at night also makes it difficult for the blood to quickly return to the heart from the muscles. Bad habits like these will lead to there being insufficient blood for the heart, making it difficult for the yang energy to enter the yin and resulting in sleeplessness.