When does sleep deprivation become dangerous

Factual Questions
1

I have heard people tend to die after about 10-14 days without sleep. But how long can you go while it is just unpleasant, but not truly dangerous?

I know the Navy seals during their training go for about 120 hours with only 4 hours sleep, and I think the sleep doesn’t start until hour 96. The reasoning was that after 4 days you run the risk of injury (the navy seals are engaging in tons of exercise during those 96 hours, so I don’t know how applicable that is to most other people). I’m assuming the navy seals designed their program with input from physicians and experts and didn’t just pull the 96 hour figure out of the air.

So is about 100 hours the time period between when sleep deprivation goes from being unpleasant to dangerous?

And what role does microsleep play in people who stay up for 2 weeks? Shouldn’t people getting microsleep or sleeping for an hour at a time let them go much longer than 2 weeks?

2

Sorry to butt in a little, but as an addendum to this question can I asked about reduced sleep (i.e. 2-4 hours a night) over a period of time, is that dangerous? What are the side-effects?

Thanks

3

Well, it can be dangerous much quicker if you say, operate a motor vehicle.

Everybody has their own amount of sleep that they work best with. REM sleep is good for you brain, but it takes awhile to kick in, and short sleep schedules or constant interruption can harm this in the short term. But your body will eventually adapt with repeated short sleep, and REM onset will be quicker. TLDR; with short sleep, your first few weeks will be crappy then you’ll feel a little better. Some people do polyphasic sleep, which isn’t without its controversy.

ETA: see the section on US military et al.

4

I just learned here in the Dope about fatal familial insomnia.

You stop sleeping, go mad and then die. :eek:

It seems that between completely stopping sleeping and death there are a few months, but they go crazy in between.

[QUOTE=wikipedia]
The disease has four stages, taking 7 to 18 months to run its course:

  1. The patient suffers increasing insomnia, resulting in panic attacks, paranoia, and phobias. This stage lasts for about four months.
  2. Hallucinations and panic attacks become noticeable, continuing for about five months.
  3. Complete inability to sleep is followed by rapid loss of weight. This lasts for about three months.
  4. Dementia, during which the patient becomes unresponsive or mute over the course of six months. This is the final progression of the disease, after which death follows.
    [/QUOTE]

So from that I would say it becomes dangerous pretty soon, but death takes quite a bit longer. I also don’t actually know what it is that kills you.

5

As a slight aside, the current issue of New Scientist has a special on sleep, and includes an article on the new sleep-reduction drugs and discussion on how much sleep is actually necessary.

I do not work for New Scientist.

6

I got 14 hours sleep last night so I guess I don’t need to worry about this anymore.

7

There is a rare (IIRC 2 reported cases) sporadic fatal insomnia where you develop the illness without having the gene.

8

At about 72 hours, you stop being able to control your staying awake. You have little 30-second “microsleeps” where your brain basically says “fuckit, I’m sleeping NOW” and shuts down for a smidge. Obviously anything requiring continual attention to prevent death (driving, operating machinery) is contraindicated after that point.

In addition, after about 45 to 75 or so hours, depending on your psychological makeup and your personal level of imagination and tendency to daydreaming (honestly) you’ll start hallucinating things - starting with minor stuff like visual shimmers, movement in the corners of your eyes, then moving up to auditory hallucinations that make sense for the area (people mumbling, doors slamming, footsteps), then moving on to classic paranoia, then moving into actually SEEING or HEARING things that aren’t there.

One of my classmates during a brutal week of theatre finals had to be talked down from her belief that a demon was standing over the pigment bins preventing her from getting the paint she needed to finish her project. She was a Catholic, so the rest of us “exorcised” the empty space for her so she would be able to continue. Obviously, hallucinations are dangerous also if they make you act in ways that aren’t matching with reality.

Animals who are deprived of REM sleep specifically do die. However, most people aren’t able to forcibly deprive THEMSELVES of sleep much past 70 to 100 hours or so, so you’re not likely to kill yourself by trying. Once you get to the point where you’re in real danger, your brain takes over and forces you down - sort of like holding your breath - you get to the point where it’s dangerous, you pass out, and breathing resumes to get you stabilized.

What is interesting is that if you’ve been sleep deprived over a long period of time, or REM-deprived (parents are especially suseptible to this since they get woken up so often) you’ll start dreaming more often, faster, and more vividly as your brain tries desperately to compensate. When people were deprived of REM for long periods, they eventually got to a point that they fell asleep, fell straight into REM, and stayed there for hours, as opposed to cycling in and out of it like normal.