The short answer? Yes, total sleep deprivation can almost certainly kill you. What's less clear is how it does it.
Before we get to the experimental and hypothetical ramifications of total sleep deprivation, let's pause briefly to address the much more pressing and pernicious issue of poor sleep hygiene, the long-term effects of which can also be deadly. THE MORE YOU KNOW, PEOPLE.
The short-term consequences of poor or insufficient sleep have been well-documented, and include diminished cognitive and motor performance, impaired memory, blunted alertness, and an increased risk of injury – not to mention blighted sex lives. If you've ever pulled an all-nighter, you've experienced these effects firsthand. But even if you rarely go a night without sleep, there's a good chance you've suffered the ill-effects of sleep deprivation.
The exact figures vary from study to study, but according to a 2011 poll conducted by the National Sleep Foundation, 43% of Americans between the ages of 13 and 64 "rarely or never get a good night's sleep on weeknights." Nearly two-thirds of Americans said their sleep needs were not being met during the week. Sixty percent reported experiencing a sleep problem on an almost nightly basis.
The side-effects associated with prolonged periods of inadequate shuteye have been shown to be cumulative, and exact a harmful toll. In one of the most extensive human sleep deprivation studies ever conducted, test subjects restricted to six hours of sleep per night for 14 consecutive days performed just as poorly on cognitive and motor tasks as test subjects who had forgone sleep entirely for two nights in a row. In the long term, poor sleep hygiene has been shown to negatively impact "the heart, lungs and kidneys; appetite, metabolism and weight control; immune function and disease resistance; sensitivity to pain; reaction time; mood; and brain function." It is a risk factor for depression and substance abuse, and has been linked to an increased risk of obesity, diabetes, heart disease and certain forms of cancer.
Most of us need seven-to-eight hours of solid sleep per night to function properly, and many of us simply aren't getting it. Falling short of sleep requirements night after night is almost certainly compromising the health of hundreds of millions of people. Though its impacts are often gradual to the point of invisibility, experts suspect that lack of sleep is, in a very real way, killing us.
Yes, you say, bored with our disquisition on the perils of poor sleep hygiene, but what about total sleep deprivation? What if I were to just stop sleeping completely? Would it kill me?
Well, yes. Almost certainly. As far as we know, however, no human has ever died due to intentional or forced sleep-deprivation. (Animals, however, have – more on that below.)
Unsurprisingly, the consequences of prolonged periods of absolute sleep deprivation are less thoroughly documented than those of merely insufficient slumber. What we do know has been cobbled together from a handful of studies, world-record attempts, and harrowing accounts like this one from psychotherapist John Schlapobersky, a consultant to the Medical Foundation for Victims of Torture who was himself tormented with sleep deprivation:
I was kept without sleep for a week in all. I can remember the details of the experience, although it took place 35 years ago. After two nights without sleep, the hallucinations start, and after three nights, people are having dreams while fairly awake, which is a form of psychosis.
By the week's end, people lose their orientation in place and time — the people you're speaking to become people from your past; a window might become a view of the sea seen in your younger days. To deprive someone of sleep is to tamper with their equilibrium and their sanity.
Accounts from victims like Schlapobersky align with those of more formal test subjects. In her 2011 essay "Up All Night," Elizabeth Kolbert recounts one of the earliest studies of Nathaniel Kleitman, a 20th Century physiologist widely recognized as the father of modern sleep research. His chosen discipline could barely be called a field at the time, but Kleitman was, by the 1930s, wholly dedicated to the systematic investigation of sleep and wakefulness. As disrupting a system is often the best way to figure out how that system works, Kleitmen's initial experiments centered largely on sleep deprivation:
In one of Kleitman's first experiments, he kept half a dozen young men awake for days at a stretch, then ran them through a battery of physical and psychological tests. Frequently, he used himself as a subject. As a participant in the sleep-deprivation experiment, Kleitman stayed awake longer than anyone else—a hundred and fifteen hours straight. At one point, exhausted and apparently hallucinating, he declared, apropos of nothing in particular, "It is because they are against the system." (Asked what he meant, he said he'd been under the impression that he was "having a heated argument with the observer on the subject of labor unions.")
115 hours is a long time, but humans have been known to tolerate significantly longer periods of wakefulness. Depending on who you ask, the world record for intentional sleep deprivation is somewhere between 11 and 19 days. The people who endure these long bouts of sleeplessness reportedly recover within a few days. No human death has been attributed to forced or intentional wakefulness... at least, not that we know of. Outcomes have, however, been fatal in rare instances when humans have been literally unable to sleep. Such is the case with fatal familial insomnia (FFI).
FFI is an exceedingly rare prion disease of the brain. Its progression is marked by a complete inability to sleep, dementia, and eventually death, with the typical survival span for FFI patients being between 7 and 36 months. Its most simplified cause is damage to the thalamus, which receives input from many sensory systems, often via the spinal cord, and relays these signals to the rest of the brain.
The disease progresses like this: insomnia, hallucinations and temperature fluctuations (sweating); complete loss of sleep; rapid weight loss; dementia and irresponsiveness, followed by sudden death.
These symptoms, and others observed in studies of sleep loss, suggest prolonged periods of wakefulness may hasten death's arrival by "the disruption of critical functions," including ones related to hypometabolism. The hypometabolic body becomes unable to appropriately manage its energy intake and expenditure. It is accompanied by dysautonomia, in which the autonomic nervous system (fight or flight) goes into overdrive, further wasting energy.
These symptoms resemble those observed in animal investigations that have looked at the detrimental effects of prolonged wakefulness. Among these investigations is a series of experiments, led by University of Chicago researcher Allan Rechtschaffen, that showed definitively that sleep deprivation could prove fatal in rats.
Results from a series of Rechtschaffen's experiments, published in 1989, showed that "all rats subjected to unrelenting total sleep deprivation died, usually after 2–3 weeks."
However, rats who were allowed no sleep at all were not the only ones to perish in the course of the experiments. The study's methods are worth recounting in detail – though, fair warning, animal lovers may wish to skip the next few paragraphs.
The researchers developed a simple mechanism to deprive rats of sleep. A 46-cm disk, divided along its diameter, was suspended over a shallow tray of water 2–3 centimeters deep. On one side of the disk the researchers would place a control rat, on the opposite side an experimental rat (the one to be deprived of sleep). The status of the rats – whether they were asleep or awake – was monitored via EEG, which measured brain activity, and EMG, which measured muscle movement. Whenever the experimental rat's brain and muscle activity indicated it was dozing off, the disk, stationary moments before, would spring to life, spinning in place a rate of 3.3 rpm. That might seem slow, but it was fast enough to bring both rats to attention and force them to move to avoid falling into the water below. In sleep-research circles, the technique is known as the "disk-over-water method." Its construction is roughly reproduced here, on the cover of Clete Anthony Kushida's Sleep Deprivation: Basic Science, Physiology, and Behavior.
The researchers tested three degrees of sleep deprivation, namely total sleep deprivation (TSD); paradoxical sleep deprivation (PSD, in which the disk turned only when the sleep deprived animal drifted into REM sleep); and high EEG amplitude non-REM (HS2D) sleep deprivation. Though none of their protocols was able to eliminate its target form of sleep completely, no sleep-deprived animal could survive any of the three forms of sleep deprivation for long. TSD animals lasted 2–3 weeks; PSD animals persisted for about 5 week; HS2D animals endured for just shy of seven weeks.
The results suggested that different parts of sleep help preserve the body's necessary functions in different ways, but all are probably required, in general. As for how sleep deprivation contributed to the rats' demise, the researchers do not present a definitive cause of death. Possible explanations include severe drops in body temperature, catabolism (the breakdown of bodily molecules prior to death), and bacterial infection. While all three of these symptoms correlated with death via sleep-deprivation, none was shown to be necessary; keeping sleep-deprived rats warm, for instance, could not save them, and artificially cooling the bodies of control rats did not kill them. The results are perplexing, and contribute to sleep's status as one of biology's most baffling mysteries.
The effects of prolonged sleep deprivation were various and troubling. The sleep-deprived rats ate more food, but lost weight. They lost the ability to maintain a healthy body temperature. Their skin deteriorated. Many sleep-deprived rats contracted bacterial diseases, though their immune systems varied when it came to type and severity of degradation. The researchers reported no obvious brain damage. If sleep-deprived rats were granted reprieve before it was too late, they could avoid death, albeit with some problems with REM sleep during their recovery.
In short, losing sleep overall killed the rats quickly; losing certain types of sleep killed the rats a little less quickly, but still resulted in death; and the various changes in physiology that were observed could not be proven to be the actual cause of death. It stands to reason that you or I would suffer the same fate, were we, heaven forbid, subjected to some scaled-up version of the disk-over-water device.
Top image via Shutterstock.