> You don't learn without problem solving ... The custodians of knowledge about how much sleep you need[, a]nd what happens if you don't get it[,] is the United States Army. Because they're extremely interested in what happens when you cross 10 or 12 times zones, and have no sleep, and have to perform. ... [A]fter the first Gulf War, which was the most studied war in history, ... there were after action reports ... full of examples like this. The US Forces ... drawn up for the night ... up for about 36 hours straight ... [w]hen, much to their amazement, across their field-of-view came a column of Iraqi vehicles ... both sides enormously surprised. A firefight broke out ... in acts of fratricidal fire. And the interesting thing is that all these folks here swore in the after action reports that they were firing straight ahead. And what happened was their ability to put ordnance on target was not impaired at all. But their idea of where the target was, what the target was, whether it was a target, was all screwed up. So this led to a lot of experiments in which people were sleep deprived. ... These are Army Rangers. It doesn't get any tougher than this.

[T]hey had ... fire control teams ... their job is to take information from an observer, over here, about a target, over here. And tell the artillery, over here, where to fire. So they kept some of these folks up for 36 hours straight. And ... they all said, we're doing great. And at that time they were bringing fire down on hospitals, mosques, churches, schools, and themselves. Because, they couldn't do the calculations anymore, after 36 hours without sleep.

And now you say to me, well I'm a MIT student, I want to see the data. So let's have a look at the data. [Slides at http://courses.csail.mit.edu/6.034f/sleep.pdf ] Very simple calculations you have to do in your head, like adding numbers, spelling words, and things like that ... after 72 hours without sleep, your performance relative to what you were at the beginning is about 30%. So loss of sleep destroys ability.

Sleep loss accumulates. So you say, well I need eight hours of sleep - and what you need, by the way, varies - but I'm going to get by with seven hours of sleep. So after 20 days of one hour's worth of sleep deprivation, you're down about 25%. ...

So you might say, well does caffeine help? Or ... naps in this case. And the answer is, yes, a little bit. Some people argue that you get the more effect out of the sleep that you do get if you divide it into two. Winston Churchill always took a three hour nap in the afternoon. He said that way he got a day and a half's worth of work out of every day. He got the full amount of sleep[, b]ut he divided it into two pieces. Here's the caffeine one. So caffeine does help.

And now you say, well, shoot, I think I'm going to take it kind of easy this semester. And I'll just work hard during the week before finals. Maybe I won't even bother sleeping for the 24 hours before the 6.034 final. That's OK. Well let's see what will happen. So let's work the numbers. Here is 24 hours. And that's where your effectiveness is after 24 hours. Now let's go over to the same amount of effectiveness on the blood alcohol curve. And it's about the level at which you would be legally drunk. So I guess what we ought to do is to check everybody as they come in for the 6.034 final, and arrest you if you've been 24 hours without sleep. And not let you take any finals again, for a year. So if you do all that, you might as well get drunk.

(Patrick Winston, lesson (#10) for the 6.034 - Artificial Intelligence course at the MIT, 2010)