One's digesting power declines in old age. Mahavira said, "Do not take dinner at night. At least the old people should avoid having dinner at night. Previously, the avoidance of dinner was regarded as a matter of religious significance, but today it has become a formula of health.
Today even the doctors recommend avoiding dinner at night, because food does not get properly digested at night. According to the principle of Ayurveda, one should not sleep till the food that is eaten goes into the digestive system. Otherwise, digestion would be adversely affected. One of the reasons of disorder in the digestive system and the problem of acidity is that a person lies down immediately after eating. He would have his dinner at 11 O'clock at night and immediately stretch himself and sleep. Even otherwise, digestion is slow during the night. Then is it surprising that there are problems of digestion if one lies down and sleeps immediately after eating? A young person can face even that situation, but when an old person does it, he only gives an invitation to illness.