* After missing one night of sleep, expect fatigue, reduced attention span and problems with short-term memory.
* After missing 2 to 3 nights, one will also suffer poor coordination, muscle twitches, marked loss of concentration, impaired judgment, blurred vision, nausea, and slurring of speech. Often one will experience episodes of microsleep (briefly sleeping for a few seconds at a time, without being aware of it).
* At about 4 to 5 days without sleep, expect extreme irritability, hallucinations, and delusional episodes.
* After about 6 to 8 missed nights, add slowed speech, tremors in limb extremities, memory lapse, confusion concerning one's own identity, unusual behavior, and paranoia to the list.
* After 9 to 11 nights without sleep, fragmented thinking occurs (beginning sentences without completing them), and prolonged episodes of unresponsive "conscious stupor."
Apparently, lack of sleep causes all of these adverse effects because it causes brain damage. During a normal day, the brain is slightly damaged by the body's metabolism, and by free radicals. When one is asleep, the brain engages a repair center which slowly mends the tiny injuries, restoring the brain to its full potential. During the deepest phase of sleep, called REM, it is believed that the repair center itself is repaired. But the longer that sleep is prevented, the more damage one's brain accrues, and the more sleep one will require to repair it. Too much damage, and it becomes irreparable.
Also there is a very rare disease called "Fatal Familial Insomnia" in which the sleep center of the brain is damaged and results in insomnia and all the symptoms above over a period of months and then eventually dementia and then ultimately death.
http://www.damninteresting.com/?p=133
So if we don't sleep ... we will die

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