If you do not sleep, you die!
If you do not sleep, you die!
Nearly everyone pulls an all nighter once upon a time. Even if this is often an unpleasant experience, it nearly always ends up with 100% recovery after a single night of solid sleep. It is therefore a bit surprising to know that a week or two of sleep deprivation can result in death! Sleep researchers constructed a cruel contraption that would wake up rats as soon as they fell asleep. This contraptions showed that it takes an average of 3 weeks to kill a rat by sleep deprivation (or some 5 months by REM sleep deprivation alone)(Rechtschaffen 1998). Dr Siegel demonstrated brain damage in sleep-deprived rats (Siegel 2003). Due to an increase in the level of glucocorticoids, neurogenesis in some portions of the brain is inhibited by lack of sleep. In short, sleep deprivation is very bad for the health of the brain.
Sleep deprivation is a well-known form of torture. Yet, for ethical reasons, the rat experiment could not be reproduced in humans (to its ultimate end). However, we have a rough idea as to the degree of human durability in sleep deprived state due to fact that we can study the effects of sleep disorders. One of them is fatal familial insomnia, in which a mutation causes the affected people to suffer from a progressively worsening insomnia that ends in death within a few months. Another example is the Morvan's syndrome in which an autoimmune disease destroys neuronal potassium channels that lead to severe insomnia and death (unless the disease progresses into remission).
You may have heard of reports of people who do not sleep at all. These reports are certainly inaccurate or false. Those who report never sleeping are either boasting or experiencing a sleep state misperception that leaves them with an illusion that they do not sleep while resting in bed.
Brain's garbage collection
Why is sleep deprivation ultimately fatal? Death of sleep deprivation is like death of an old age in general. Very often, multiple causes conspire to produce the final inevitable outcome. Probably nobody knows the exact answer to this mystery. However, research into the role of sleep gives us pretty strong hints.
During the day, we learn new things, memorize, acquire skills, figure things out, set new memories through creative associations, etc. After a long day of waking, the brain is full of disorganized pieces of information that need to be integrated with things we have learned earlier in life. Without this re-organization, the brain would harbor chaos, and would quickly run out of space to store new memories. This neural role of sleep is so fundamental that sleep deprivation affects nearly all functions of the body that are governed by the nervous system. Without a regular garbage collection, individual networks begin to malfunction. These initially minor malfunctions can add up to a serious problem for the entire organism. Most prominent effects of sleep deprivation are problems with thermoregulation, decline in immune function, hormonal changes (e.g. increase in glucocorticoids and catecholamines), metabolic changes, malnutrition, hallucinations, autonomic system malfunction, changes in cell adhesion, increase in inflammatory factors (e.g. IL-6, TNF, C-reactive protein, etc.), skin lesions, oxidative stress, DNA damage, etc. Those problems become serious enough to kill. Metaphorically speaking, if we compared a less developed organism to a WW1 bomber, we could imagine that the process of evolving into a human being is like acquiring the software needed to fly a B-2 bomber. Even though B-2 is ages ahead of a plane constructed during the life of Orville Wright, it is enough to plant a bug in its software to make it fall out of the sky. Human body in sleep deprivation is like a B-2 with a progressive software malfunction. It may be technologically advanced, it may be smart, and yet it is very vulnerable. The reliance on advanced software or neural function is always dangerous! Luckily, all we need to eliminate the danger is to just go to sleep every day. For more see: Neural optimization in sleep.
There is a second layer of trouble in sleep deprivation. Due to the importance of sleep, all advanced organisms implement a sleep protection program. This program ensures that sleep deprivation results in unpleasant symptoms. It also produces a remarkably powerful sleep drive that is very hard to overcome. Staying awake becomes unbearable. Closing one's eyes becomes one of the most soothing things in the universe. Are these symptoms a result of network malfunction? Definitely not. If they were, the drive to sleep might malfunction as well. Moreover, recovery from sleep deprivation would not be as fast, as easy, and as complete! Sleep protection program is there, and it can make the effects of sleep deprivation worse. Like a cytokine storm in an overzealous immune system, sleep protection program can potentially add to the damage caused by the network malfunction in sleep deprivation.
Last but not least, sleep has evolved to become a chief anabolic state of the organism. Without it, the body keeps using itself up, without much time to rebuild. Turning on anabolic state does not require turning off the consciousness, however, the time of night rest seems to be the best time for the body to do all the rebuilding. As we must sleep anyway, that anabolic functions became consolidated with other functions of sleep, and now may be indispensable. The anabolic state, and the nighttime increase in GH or testosterone, also affects the neural networks and the status of our "mind software". Hormonal changes stimulate and/or inhibit neural growth. Dr Michael Stryker, best known for demonstrating the role of sleep in brain development (Stryker et al. 2001), says that nighttime hormonal changes may "play a crucial role in consolidating and enhancing waking experience". One of the leading causes of death in sleep deprivation seems to have been opportunistic bacterial infections caused by a decline in the immune function (e.g. no febrile response). That decline could be caused equally well by (a) poor neural control of the immune function or (b) straight effect of hypercatabolism. Whatever the cause, scientists have quickly figured out that application of antibiotics did not help much in preventing death from those infections. Sleep deprived rats would die anyway. The infection might speed up death that was otherwise inevitable.
Why do we die without sleep?
It is impossible to quantify the contribution of those three factors to the fatal outcome of prolonged sleep deprivation:
- network malfunction, or
- secondary effects of sleep protection program, or
- continuous catabolic state.
Even though the latter two could possibly be remedied pharmacologically, there is no way around network remolding in sleep. Researchers who hope to find a remedy against sleep are plodding a blind path. Without some serious nanotechnology bordering on science fiction, sleep is here to stay with human race for many years to come. Even though, sleep deprivation could kill, sleep is good news. It makes us smarter! We should all embrace the blessings of healthy unrestrained sleep. After all, there are few better things in life than a good night sleep after a well-spent day. Sleep should be listed among basic human rights!
- Rechtschaffen A., "Current perspectives on the function of sleep", Perspectives in Biology and Medicine / Volume 41 / Issue 3 (1998): 359-90
- Siegel J.M., "Why we sleep," Scientific American / Volume 289 / Issue 5 (2003): 92–97
- Hairston I.S., Little M.T.M., Scanlon M.D., Barakat M.T., Palmer T.D., Sapolsky R.M., and Heller H.C., " Sleep restriction suppresses neurogenesis induced by hippocampus-dependent learning," Journal of Neurophysiology / Volume 94 / Issue 6 (December 2005): 4224-4233.
- Frank M.G., Issa N.P., and Stryker M.P., "Sleep Enhances Plasticity in the Developing Visual Cortex," Neuron / Volume 30 / Issue 1 (April 2001): 275-287
- Whitfield J., "To sleep, perchance to learn," Nature (April 2001), doi:10.1038/news010426-15