The brain’s sensory systems are geared towards detecting the presence of objects, rather than their absence: when an object encroaches on your visual field, generally speaking, neurons in your visual cortex are activated. Moreover, this bias towards detecting objects has been reflected in scientific interest in the topic: most neuroscientific... See more

There are endokrine signal involved to signal hunger and satiety. The archuit nucleus release chemicals that act as brakes and accelerators of hunger. - The PMOC neurons (system) produce a-MSH, which reduces appetite and get active while eating. They are activated by ultra-violate light to the eyes, which explains the lower hunger and appetite in... See more

According to one theory, it is in the organism’s best interest to remain ignorant, and sleep exists to prevent us from acquiring unnecessary knowledge.