Explanation:

The energetic bodies of angels do not have a digestive and respiratory systems to carry on the oxidation of food to generate inert energy which is the working element in the nervous system-machine to generate the awareness. Since angels travel in the region of vacuum also above the region of air, the respiratory system is impossible. The electromagnetic radiation travels even in vacuum, without air and hence the energetic body of the angel travels in vacuum, without air. Since angels do not take any food, neither air nor food is available for the generation of inert energy. These angels said to be the drinkers of cosmic energy (ushmapayinah). This means that the energetic bodies take the inert energy directly from cosmic energy, which enters the subtle nervous system and generates awareness. Since the human body does not have the ability to take cosmic energy directly, the food and air are required for the generation of inert energy. Hence, the awareness in a human body disappears in the absence of food and air. In the case of angels, since the inert energy is directly taken, the awareness is continuous even without food and air. The angels are called as animishas, which mean that their eyelids are never closed. This means that they never sleep. Hence angels are said to be relatively eternal compared to human beings.