Copyright © 2007-2017 Russ Dewey
Effects of sleep deprivation are not as severe as once thought. Most people can pull an all-nighter (stay up one night) with no ill effects other than extreme sleepiness. But most people have trouble staying up for more than 48 hours.
Long walks, exposure to cold, and attention-grabbing stimuli will keep a person awake after 48 hours. After 100 hours (4 days) only constant prodding will keep people from dozing off.
What happens as the amount of sleep deprivation increases?
Many studies show that subjects can compensate well for the effects of sleep deprivation. However, the number of mental lapses increases steadily as the amount of sleep deprivation increases. That can be dangerous if a person is driving or operating machinery.
These mental lapses are moments when a person does not respond to a signal from the experimenter or "drifts off" and forgets to concentrate on an assigned task. Webb (1981) called these "involuntary rest periods." Others call them microsleeps
Researchers in Britain kept a group of young adults awake for three days and studied their performance on a variety of laboratory tasks. Some required problem-solving, others tested memory, motor coordination, and vigilance (ability to maintain concentrated attention).
An interesting pattern emerged. The tasks that proved difficult after losing a night of sleep were boring tasks. With intellectually challenging or physically demanding tasks, subjects showed no effect of sleep deprivation.
However, if subjects had to press a button every minute or so when they heard a soft tone (a boring task) they kept drifting off. That may explain the prevalence of sleepiness in certain classes where students are expected to passively absorb information they do not find very interesting.
What pattern emerged in a British study of sleep deprivation?
Unfortunately, when a person is sleep deprived, events are more likely to seem boring. A person with no sleep deprivation "will probably not fall asleep even in the most boring of lectures" according to sleep researchers (Adler, 1993).
However, a person deprived of sleep is likely to find the same lecture boring. That person may get almost uncontrollably sleepy.
Only a handful of people have remained awake over 200 hours (8 days). A famous case is that of Peter Tripp, a New York disk jockey, who vowed to stay awake for 200 hours to raise money for the March of Dimes.
Tripp was closely monitored by sleep researchers (including Dement) and was tested in various ways. By 100 hours he was already hallucinating.
Tripp managed to finish his 200-hour ordeal, slept for 13 hours, and awoke feeling normal, although he reported a slight depression that lasted for three months afterward. Tripp's hallucinations may have been due to amphetamine drugs he was taking (under the supervision of doctors) to keep himself awake.
Five years later, a young man named Randy Gardner tried to break the world record for sleeplessness. While sleep researchers observed him and monitored his body functions, he went over 260 hours without any drugs or any ill effects except mental lapses.
How did the experiences of Tripp and Gardner contrast?
For example, on day 11, Gardner was asked to count backwards from 100 by 7s, a standard cognitive test. He stopped at 65, saying he had forgotten what he was doing.
Unlike Peter Tripp, Gardner experienced no hallucinations. He slept fourteen and a half hours after his sleepless period and seemed normal after that.
True insomnia is characterized by three things, according to professionals: (1) persistent sleep difficulty, (2) adequate sleep opportunity, and (3) associated daytime dysfunction. The dysfunction might include:
Of course, many of those problems could be reported by somebody without insomnia. A firm diagnosis requires a night or two at a sleep laboratory.
People are notoriously bad at estimating the amount of time they spend asleep. They may believe they have insomnia or difficulty sleeping, when objective evidence shows they do not.
In a nationally representative sample in the United States, 35% of adults claimed they were afflicted by insomnia within the previous year (Mellinger, Balter, and Uhlenhuth, 1985). In a similar survey of "1,006 representative households in the Los Angeles metropolitan area" 42.3% of respondents complained of insomnia.
However, when self-reported insomniacs stay overnight in a sleep laboratory, EEG recordings reveal they are drastically underestimating the amount of time they spend asleep. Smith (1979) wrote:
...A woman with a 25-year history of insomnia...entered [a sleep] laboratory. In four successive nights, she fell asleep quickly, slept more than eight hours per night, and had normal architecture of sleep stages....Each morning, however, she reported that she "didn't sleep a wink." Patients consistently exaggerate their insomnia...
A study of 122 drug-free subjects who complained of chronic insomnia found the group was indistinguishable from the normal population in average time asleep. They averaged over 6 hours of sleep per night. Few got less than four hours of sleep (Carskadon, Dement, Mitler, Guilleminault, Zarconi, and Spiegel, 1976).
What is usually true of people who claim to be insomniacs?
Carskadon and colleagues found that their group of self-reported insomniacs had many nighttime awakenings. The number increased with age, from 12 per night in the 18-29 age group to an average of 25 in the 60-68 age group. The researchers wrote:
Without exception, subjects consistently underestimated the number of arousals. No significant correlation was found between the recorded and estimated number of arousals in women or men. (Carskadon et al., 1976)
What accounts for the impression many people have that they are insomniacs?
Ponder that statement for a moment. The subjects "without exception" were waking up more often than they realized. When asked the next day how often they had awakened during the night, they had no clue (the estimates were not even correlated with the number of actual arousals).
Yet these were people who called themselves insomniacs. Evidently what they were calling insomnia was awakening many times during the night.
That is Webb's (1981) conclusion also. He describes pseudo-insomnia (false insomnia) as a complaint of "no sleep" which turns out to be frequent awakenings in an otherwise-normal succession of sleep stages.
During each awakening the individual evidently thinks, "I'm still awake; I haven't slept a wink." But actually such people are averaging about six hours of genuine sleep per night.
The syndrome of reported insomnia, contradicted by objective evidence, has its own diagnostic category: sleep state misperception. In DSM-5 this was replaced by the term paradoxical insomnia. Conroy and Culebras (2016) summarize the disorder this way:
Paradoxical insomnia (previously called sleep state misperception) is characterized by complaints of little or no sleep over long periods of time without the level of impairment expected with such a level of sleep deprivation.
...Sleep study reveals normal sleep architecture with normal sleep onset latency and sleep efficiency, but with subjective patient reports indicating prolonged sleep onset latency and poor sleep efficiency. Treatment usually involves patient reassurance.
Are sleep rhythms triggered by the environment? What happens to sleep rhythms if people are cut off from all day/night cues?
To find out, Czeisler, Weitzman, Moore, Zimmerman, and Knauer (1980) studied 12 male subjects who lived from 16 to 189 days in rooms deep below the earth. They were cut off from any indication of time. The subjects set their own daily rhythm. They turned lights on or off, went to bed and got up when they pleased, all without time clues.
All 12 deviated from the usual 24 hour rhythm. But all settled on a daily rhythm. Most ended up with a day that was about 25 hours long.
What did Czeisler and colleagues find out by depriving male subjects of time clues?
The subjects showed regular temperature variations during the day. Their body temperatures rose to a peak once a day and fell to a low point once a day. Almost all the subjects woke up when their body temperatures were rising.
Length of sleep did not depend on how long a subject stayed awake before sleeping. Instead, it depended on body temperature.
If a subject went to sleep at the low-
However, if a person went to sleep when his body temperature was high, he slept for an average of 14 hours: through the hot temperature period, then the next low temperature period, then waking up when body temperature was rising again.
Why might it be wise to go to bed when your temperature is low?
This pattern suggests that people who sleep more than 10 hours at a time might be going to sleep when their temperature is high. It also implies that the most efficient approach is to go to sleep when the body temperature is low. That is when people tend to feel tired and unable to concentrate on work anyway.
The circadian rhythm is 24 hours. However, the research above (by Czeisler and colleagues) showed the body's internal clock produces a cycle of 25 hours, when left on its own.
Evidently our daily rhythm is driven by the slightly faster circadian or 24 hour rhythm. The light/dark cycle acts as a pacemaker by influencing production of melatonin. Without the light/dark rhythm, humans easily adopt a 25 hour rhythm
Due to the 25-hour natural rhythm, humans easily shift their sleep schedule forward (getting up later and later) but have trouble shifting it backward. This produces a phenomenon known as Sunday night insomnia.
If you stay up late and sleep late over the weekend, you can easily adjust your body rhythm forward one or two hours a day. Over the weekend you can shift your internal clock forward up to four hours, so midnight feels like 8 p.m. when you go to bed Sunday night.
What causes "Sunday night insomnia"?
For people who cannot break out of the pattern of remaining awake until wee hours of the morning, sleep rhythms can be reset by moving the rhythm forward instead of backward. An insomniac who normally stays up until 3 a.m. might be asked to stay up until 5 a.m. before going to bed.
The next day, bedtime is 7 a.m., the next day 9 a.m. Eventually such a person can work around to a normal bedtime. This works in some cases when everything else fails.
Czeisler, Moore-Ede, and Coleman (1982) applied findings about the ease of "shifting forward" to solve problems at the Great Salt Lake Minerals and Chemicals Corporation in Ogden, Utah. Workers at this plant were bothered by weekly shift rotations requiring them to change from night to evening and then to a day schedule.
Czeisler and the other researchers realized the backward shifting was fighting natural rhythms of the body. They tried reversing the pattern. They had workers move from day to evening shift, then from evening to night. Instead of getting up earlier for a new shift, workers stayed up later.
The workers liked this better. Job satisfaction ratings improved, employee turnover at the plant decreased, night production improved, and health complaints went down.
How did Czeisler use this knowledge to solve a problem involving shift workers?
For similar reasons, it is easier to recover from jet lag–the feeling of being on a different time schedule than the rest of the world–when flying from east to west. When you fly west, you get to stay up later...unless you fly more than halfway around the world! Then you might end up on an earlier schedule.
The chemical melatonin is produced by the pineal (pie-NEE-al) gland. When melatonin levels in the bloodstream are high, people fall asleep relatively easily.
The production of melatonin in the brain is regulated by a structure in the hypothalamus (the suprachiasmatic nucleus). It receives inputs from the eyes. Daylight suppresses melatonin release, so ordinarily people do not fall asleep easily in the daytime–except for a drowsy time in the middle of the afternoon.
How does melatonin relate to sleep?
Melatonin production increases around 9:30 p.m. in older adults, 10:30 p.m. in adolescents. Most people can fall asleep quickly at that time.
People with a sleep disorder called the "delayed sleep phase syndrome," who typically fall asleep around 4 or 5 a.m., can often be helped by taking a small dose of melatonin around 10 in the evening (Haimov and Lavie, 1996).
Melatonin is readily available as an OTC (over the counter) supplement. However, the doses are often much too high.
MIT researchers found, in a careful double-blind study in 2001, that melatonin "worked" when taken around bedtime. But the optimal dose was .3 milligrams.
Typical melatonin pills sold in drugstores ranged from 1 to 3 milligrams (and still do). The MIT News Office explained the consequences of that dosage in 2005:
At that dose, "after a few days it stops working," said Wurtman, director of MIT's Clinical Research Center and the Cecil H. Green Distinguished Professor. When the melatonin receptors in the brain are exposed to too much of the hormone, they become unresponsive. (Halber, 2001)
How much of a typical 1 mg melatonin tablet would be optimum, to relieve insomnia?
Dr. Wurtman now sells his own brand of low-dosage melatonin pills. However, a less expensive approach is to buy typical 1 milligram pills and take a third of one each night.
Carskadon, M. A., Dement, W. C., Mitler, M. M., Guilleminault, C., Zarconi, V. P., & Spiegel, R. (1976) Self reports vs. sleep laboratory findings in 122 drug-free subjects with complaints of chronic insomnia. American Journal of Psychiatry, 133, 1382-1388.
Czeisler, C. A., Moore-Ede, M. C., Coleman, R. H. Rotating shift work schedules that disrupt sleep. Science, 217, 460-463.
Czeisler, C. A., Weitzman, E. D., Moore-Ede, M. C., Zimmerman, J. C., & Knauer, R. S. (1980) Human sleep: Its duration and organization depend on its circadian phase. Science, 210, 1264-1267.
Halber, D. (2001, October 17) Scientists pinpoint dosage of melatonin for insomnia. MIT News [blog] Retrieved from: http://news.mit.edu/
Mellinger, G. D., Balter, M. B. & Uhlenhuth, E. H. (1985) Insomnia and its treatment. Archives of General Psychiatry, 42, 225-232.
Smith J. R. (1979) Sleeping pills and insomnia. Science, 205, 7-8.
Webb, W. (1981). Sleep Disorders and Modes of Treatment. Riverside, CA: Psychological Seminars, Inc.
Write to Dr. Dewey at firstname.lastname@example.org.
Copyright © 2007-2017 Russ Dewey