Under serious sleep deprivation your short-term memory goes all to hell. During one exercise I remember being unable to follow simple verbal instructions because I couldn't remember the complete instruction.

Faced with three different colored balls and three different colored boxes and told to: 'Pick up the red ball and put it into the yellow box' I would pick up the red ball and have no idea what I was supposed to do with it. Or if I picked it up and walked to the yellow box I might not remember what I was supposed to do. It is a strange sensation finding a ball in your hand and that your standing in front of a yellow box. Remembering your supposed to do something but not knowing what it is.

The trick was to write instructions and messages down in simple steps and to check off the steps as each is completed. Written instructions can be reviewed so if you forget the first part you can look back at it. It works better if you work in pairs. One person reading and checking and the other doing the work.

Ironically long-term memory seems less effected. Told to repeat a thirteen digit number many times over a twenty minute period the person can recite this number a day later even when the learning and recitation was during a deeply sleep deprived period.

Also previously learned skills that have made it into muscle memory and routine, like field stripping and reassembling a weapon and sometimes driving, are also relatively unaffected. You might be unaware you are doing the job. Effectively sleeping with your eyes open while you do it. It has been noted that chronic drunks often drive home in a similar autopilot state of mind. As long as the task is free of variations from the trained routine it gets done in the normal manner. If something is changed the person is often completely unable to cope.

It is also interesting to see how people can stand up, march and complete simple jobs while being, for all practical purposes, asleep. It is fascinating to see the degree with which the primitive brain still prevent a person from doing things that would directly harm themselves or violate ethical norms. Although completely unaware of the situation it is next to impossible to get someone to put their hand into a fire or march off an obvious cliff. Told to do so they simply stop. If questioned they have no understanding of the situation, what they were told to do or stopping.

It is pretty funny to watch this sort of 'march of the zombies' behavior. Very strange to be playing the part of the zombie. I remember it as if it were a series of disconnected snap-shots of something done by someone else.

It is pretty hard to keep a person from getting any sleep after a couple of days. It becomes a full-time job just to keep one person awake all the time. As soon as they are not actively engage they catch a series of tiny cat naps. Often less than a minute each. People can sleep a few minutes at a time while hiking and standing up. These add up to significant amounts of sleep over a 24 hour period. Actively kept from getting any sleep at all people become delusional in just a few days. If people can slip in a few minutes of light sleep every few hours they can go much longer.

But inevitably everyone goes a bit nuts and becomes subject to hallucinations and delusions if kept from sleep long enough. In extreme cases people who have tried to break the sleep deprivation record have become dangerously insane. One guy jumped through of a second-floor picture window thinking the building was on fire. A few apparently became at least semi-permanently deranged. This is supposed to be why the Guinness Book of Records no longer lists the record for going without sleep. It isn't clear if they weren't deranged before they went for the record. Anyone who would voluntarily try to stay awake for over a week has to be a bit strange to begin with.

Most people recover completely as long as they get some sleep before they become delusional. Most people don't get that far. Unless someone is actively preventing them from getting sleep most people find it impossible to get to that stage. The body just shuts down and they doze off for at least a short time.