Consuming food, water etc. at night is strictly prohibited in the Jain Dharma. There are many reasons for this prohibition. The germs and microbes that disappear when there is sunlight do not really get destroyed; they take shelter in shadowy places and after the sunset, they enter and pervade the atmosphere. These microbes are invisible to the naked eye, get into our food. Consuming this kind of food will lead to killing of these germs and bacterias which in turn will lead to our ill health.

Our biological clock is set according to the sunrise-sunset. When the sun is right above us, our digestive fire performs at its peak. The food eaten at night time does not get properly digested since the digestive system becomes inactive during the night owing to the absence of sunlight and we face the problem of indigestion. The metabolism rate slows down during these hours as we do not indulge in any physical activity which helps in digestion. Hence, due to these reasons the food taken during night times does not get digested; and its putrefaction in the body is harmful to health. This leads to increase in weight as the undigested food gets stored in the form of fats. It also leads to foul smell in the breath, putrefaction of teeth, constipation, pain in knee joints and several diseases of the throat.
Indian Science of health has formulated a rule that after having taken food, one should drink little-little water many times. Eating food before sunset allows this practice naturally. Some scientists also say that you should avoid food atleast 3-4 hours before sleeping, so that the food gets digested properly before sleeping. A recent research in Hong Kong proves that people eating food by early evening are less prone to heart diseases.

Other scientific reasons to avoid food at night:

1. Fluctuations in Sleep Cycle:
Another important reason why you may want to avoid eating late is due to the effect it can have on your sleep cycle. Research has found that the digestive process can have serious implications on your sleep cycle, causing you to wake up more often, and have a harder time falling asleep in the first place.

2. Increased Urination and Excretion Needs:
Drinking water and eating food late night would lead to an increase in the number of times that you may need to get up to use the restroom during the night. Also, it will result in food being digested during your sleeping hours—and because of this, you may need to wake up to eliminate the waste products.