I figured I might be able to contribute a bit to this (older) thread, and there doesn't seem to be too much going on in this part of the forum, so I don't feel bad resurrecting an old thread (it's still on the first page!)
I did a sleep deprivation experiment on myself about three years ago back when I was in university. I wound up staying awake for a little under 4 days before I crashed, and kept a log of what was going on up to 90 hours.
This was done in my apartment-style school residence, and because there was always some sort of action going on, I was only alone from about 3-6am, except for the day I eventually crashed. Being alone is what eventually did me in. If anyone is considering doing this, it's a lot easier if you have people around to talk to you or that can do something with you, just so your mind doesn't drift off. Just make sure they know you'll get irritable so they don't get offended. During my alone hours I tried to watch a movies or TV, or play video games, to keep myself from sleeping. Try not to do too much physical activity (although sometimes a bit is useful for waking up), and wear loose comfortable clothing. After 48 hours or so you probably don't want to leave your home.
I've edited this for spelling/grammar, as well as clarity for those who don't know my room setup,etc. Anything in italics was written while I was staying awake.
PROLOGUE: THE FIRST 48 HOURS
Saturday, 6PM -0 HR- After a late Friday night, I wound up in bed in the early morning and then slept till 6PM. I got up, and decided that I would stay up till around 9 or 10 the next night to "reboot" my sleep schedule.
Sunday, 12PM -18 HR- Decided that I would try to stay up as long as I could.
I'd often pulled all-nighters for school, so the first day wasn't remarkable for anything.
Monday, 5AM -37 HR- Was feeling tired, so I took a shower. The shower really woke me up; it wasn't cold or anything, but made me much more alert.
Monday, 2PM - 40-44 HR- In class, periodically I had very heavy eyelids, and had difficulty paying attention. Jumpy legs. At other times, didn't feel tired at all.
THE NEXT COUPLE OF DAYS: STRANGE THINGS BEGIN TO HAPPEN
Tuesday, 12AM -54 HR- Accidentally put away two of my textbooks with my socks, after doing laundry. I can't remember doing it, and this is the first example of me doing something a little strange.
Tuesday, 6AM -60 HR- (Note: I was sitting in my room watching a movie on my computer, I looked over at my door and the wall. The door and the wall were painted the same solid blue colour, with a dartboard mounted on the back of the door.) First visual anomaly: I looked at the wall, the dartboard appeared normal, but the wall was different, like without distance... it wasn't close to me, or far away, and it didn't line up with where the dartboard was (so the dartboard appeared to be floating), I really couldn't judge how far away it appeared. The dartboard was the proper distance.
Tuesday, 6AM -60 HR- Shortly after the above, a strange smell, like nothing I've ever smelled before, suddenly appeared and then suddenly disappears. Smell was not pleasant, nor offensive - I really can't describe it.
Tuesday, 7AM -61 HR- Feeling very tired, so decided to take another shower to wake me up. Shower woke me up again, my imagination seems to be running wild - a hair on the wall of the shower with a drop of water on top immediately appeared to me to be a nose and moustache. I needed to actually think to figure out what it was. I seemed to read a lot into shapes, seeing especially faces in random folds of the shower curtain, etc.
(Note: I was not been under any impressions that what I saw there actually happened, i.e. i didn't think "there is a face on the wall" i thought "that looks like a face on the wall," but knew that it wasn't. Seeing faces in things was sort of a recurring thing after this point. Anything that was even remotely shaped like a face I would see like a face. At one point I confused a roommate by calling the taps in the kitchen sink "eyes" - the taps were the eyes and the faucet was the nose, you see.)
Tuesday, 10AM -64 HR- Got really tired, fairly quickly. Balance feels a bit off for the first time
Tuesday, 3PM -69 HR- fully awake and alert for some time
Tuesday, 4PM -70 HR- zoned out, balance off again
Tuesday, 7PM -73 HR- still dizzy, very sleepy, eyelids heavy, eyes burning
Tuesday, 10PM -76 HR- easily spaced out by anything, shifting gaze makes me dizzy, peripheral vision appears slightly "wavy."
Wednesday, 2AM -80 HR- Sensations feel different, like they're felt by another person and delivered to me over a large distance and with a short delay. (Note: I don't think that that was a very good description of what I was feeling... it was almost as if I was seeing and feeling through a TV set, kind of removed from myself) Peripheral vision changed from "wavy" to "jumpy"
Wednesday, 6AM -84 HR- Watching a movie is difficult, my mind keeps wanting to wander off, and it's like i'm watching half of the movie, and inventing the other half it doesn't really make sense.
Wednesday, 7AM -85 HR- While watching a movie, the people "stopped speaking english", it sounded like they were speaking gibberish, but I still understood what they were saying.
EPILOGUE: I GO A LITTLE CRAZY
Wednesday, 10AM -88 HR- Pile of clothing on bed seems like it's trying to jump on me... I had to mess it up so it won't.
Wednesday, 2?PM -90? HR- Felt threatened by pile of clothing on bed, it wanted to "grow a new dimension." I tried to reason with myself but it still bothered me. Messed the clothes up.
These last two deserve some explanation: I had put a big pile of clothes on my bed to keep myself from laying on it and falling asleep. From the desk in my room where I was sitting, this pile was just in my peripheral vision, and it seemed like the pile would keep jerking towards me, startling me and making me turn towards the clothes. Eventually I had to mess the pile up so I didn't feel like it was going to jump on me. After a few hours, I felt very threatened by the clothes on my bed, believing them to be plotting against me (I know... crazy)
Unfortunately, all of my roommates were out of the apartment at class (I was in no shape to go to class) so I was alone on Wednesday, and that proved my undoing. When my roommates got home a couple of hours later, they found me passed out on my bed, clothes scattered all over the floor. They let me sleep.
Even though I didn't mention it, I felt very irritable after about 48 hours, and staying awake wasn't a pleasant experience. I'd recommend it if you want to see how far you can push yourself (the record for staying awake is like 11 days) but it's not something to do for fun.