Learning and memory: Sleep helps the brain commit new information to memory through a process called memory consolidation. In studies, people who’d slept after learning a task did better on tests later. Rest helps the brain get rid of waste products produced during the waking hours because while the rest of the body has a lymphatic system, the brain does not so clearance of waste products via the Cerebrospinal fluid is maximal at rest when the brain sulci become larger.
Metabolism and weight: Chronic sleep deprivation may cause weight gain by affecting the way our bodies process and store carbohydrates, and by altering levels of hormones that affect our appetite.
Safety: Sleep debt contributes to a greater tendency to fall asleep during the daytime. These lapses may cause falls and mistakes such as medical errors, air traffic mishaps, and road accidents.
Mood: Sleep loss may result in irritability, impatience, inability to concentrate, and moodiness. Too little sleep can also leave you too tired to do the things you like to do.
Cardiovascular health: Serious sleep disorders have been linked to hypertension, increased stress hormone levels, and irregular heartbeat.
Disease: Sleep deprivation alters immune function, including the activity of the body’s killer cells. Keeping up with sleep may also help fight cancer.