If a person misses two nights of sleep it gets worse.
Concentration is difficult and attention span falls by the wayside.
After three days a person will start to hallucinate and clear thinking is impossible. With continued wakefulness a person can lose grasp on reality. Rats forced to stay awake continuously will eventually die, proving that sleep is essential. A person who gets just a few hours of sleep per night can experience many of the same problems over time. Two other things are known to happen during sleep.