You must have noticed that you feel very sleepy after you have eaten a heavy meal. All you want to do is to lie down and sleep. Why is it so? There is a scientific sexplanation to this condition. An average adult has about five litres of blood, which circulates in his body. The quantity of blood that goes to different parts of the body is not fixed. Under normal conditions, the liver receives 28% of the total heart output; kidneys, 24%; muscles, 15%; brain, 14%; and the remaining 19% goes to the other parts of the body. However, this quantity may change depending upon the requirement of the body organs. After having a meal, a large quantity of blood goes to the stomach as it requires more blood for digestion. This causes a deficiency of blood in the brain. And so, the brain becomes less active. This induces sleepiness. In fact, it is a signal to the body to take rest.