I travelled to Haifa yesterday by train, and on the way reread parts of 'Why we sleep'; something that I noticed previously but didn't really pay attention to, stood out. Chapter 7 of the book is entitled 'Too Extreme for the Guinness Book of World Records: sleep deprivation and the brain', and in it, an experiment is described that measures concentration.
All of the subjects started off by getting a full eight-hour sleep opportunity the night before the test, allowing them to be assessed when fully rested. Then, the participants were divided into four different experimental groups. Rather like a drug study, each group was given a different “dose” of sleep deprivation. One group was kept up for seventy-two hours straight, going without sleep for three consecutive nights. The second group was allowed four hours of sleep each night. The third group was given six hours of sleep each night. The lucky fourth group was allowed to keep sleeping eight hours each night.
Those individuals who slept eight hours every night maintained a stable, near-perfect performance across the two weeks. Those in the three-night total sleep deprivation group suffered catastrophic impairment, which was no real surprise. After the first night of no sleep at all, their lapses in concentration (missed responses) increased by over 400 percent. The surprise was that these impairments continued to escalate at the same ballistic rate after a second and third night of total sleep deprivation, as if they would continue to escalate in severity if more nights of sleep were lost, showing no signs of flattening out. But it was the two partial sleep deprivation groups that brought the most concerning message of all. After four hours of sleep for six nights, participants’ performance was just as bad as those who had not slept for twenty-four hours straight—that is, a 400 percent increase in the number of microsleeps. By day 11 on this diet of four hours of sleep a night, participants’ performance had degraded even further, matching that of someone who had pulled two back-to-back all-nighters, going without sleep for forty-eight hours.
Ten days of six hours of sleep a night was all it took to become as impaired in performance as going without sleep for twenty-four hours straight. And like the total sleep deprivation group, the accruing performance impairment in the four-hour and six-hour sleep groups showed no signs of leveling out.
I think back to my days of basic army training: we were allowed 6 hours sleep each night, although this is not what happened. It actually means that evening activities ceased at 11 pm and recommenced the next morning at 5 am. There are obviously a few minutes required to get undressed in the evening, but we would fall asleep immediately. It does not include any time for showering, so normally we went without. More importantly, it does not include being woken up in the middle of the night for an hour's guard duty; the most lucky were those who had the first shift (i.e. they stayed awake for an hour then had five hours of uninterrupted sleep), then those who had the last shift. Everyone else fell asleep, got woken up for an hour's walking around, then went back to sleep again an hour later. I don't remember the frequency of guard duty: if there are 40 soldiers in the platoon, six hours to guard and two people per hour, then we would have guard duty once every three to four nights. Of course, more soldiers meant a lower frequency. This went on for several months. No wonder we used to fall asleep at any opportunity. There was a certain amount of time (say 15 minutes) in the early morning between running, breakfast and the daily expection, when one could clean oneself, polish boots and similar, as well of course cleaning up the tents, etc.
In reserve army duty, when it was guarding (as opposed to my first easy years working in a laboratory), it was most frequently four hours on and eight hours off. This later became amended to: between 6 am and 6 pm, four hours on and eight hours off (there were three platoons). Between 6 pm and 6 am, three hours on and six hours off. So, if one guarded from 6 am - 10am, one would also guard from 6 pm - 9 pm and then again from 3 am to 6 am; 10 hours out of 24. This went on for a few weeks.
The point that I am trying to make is that we were sleep deprived; our powers of concentration were shattered, so how exactly were we supposed to learn and internalise what we learned during basic training, or act appropriately during guard duty?
I know that the sleep deprivation during basic training is one method by which the individual is 'broken down' then gets reintegrated into a unit, but it has always seemed somewhat cruel.
I wonder whether the orders about sleep are still the same; I wouldn't be surprised if nothing has changed despite all the research into sleep deprivation during the last forty years.
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