Written by Micah Sadigh, PhD on November 02, 2019
I hope you don’t mind the somewhat academic nature of this article. But we are currently learning so much about the complex nature of sleep that it is important to stay close to the latest developments in the field by examining scientific publications while discussing the topic.
According to the National Center for Chronic Disease Prevention and Health Promotion, more than 70 million Americans suffer from persistent insomnia or inability to sleep. In a sense, we are a nation of insomniacs, and the problem is not going away—it is getting worse. Sadly, people who suffer from chronic insomnia often are not properly diagnosed, and, even worse, they may be placed on hypnotics (sleeping pills) for an extended period or resort to various maladaptive approaches to address their insomnia. Those “maladaptive” approaches tend to work initially but, in the long run, cause more problems, even serious ones.
When I conducted my first sleep study on the consequences of rapid eye movement (REM) deprivation, some of our findings, which included memory deterioration, weight gain, and aggression, were hard to explain. (By the way, at that time, the participants in my study were a group of rats!) However, those same findings were observed in human participants a few years later. Today we have a pretty good idea as to why these symptoms (changes in memory, weight gain, and aggressive tendencies) and others may present themselves when we are sleep-deprived.
It should initially take between 10 and 15 minutes to fall asleep. Most people need about 5 to 6 cycles of sleep daily, each of which lasts about 90 minutes. While minor interruptions occur between some sleep cycles, we should be able to fall back to sleep quickly.
Generally speaking, our sleep can be divided into 2 phases:
Non-rapid eye movement (or NREM) sleep
Rapid eye movement (REM) sleep
While for some time it was thought that we dream only in REM sleep, we now know we dream in both NREM and REM sleep. However, it is more difficult to recollect dreams that occur in NREM sleep, particularly in its deeper stages.
Although we still do not know exactly why we sleep, we have ample data on what happens to us when we are deprived of this complex and fascinating state of consciousness.
Some of the complications that are brought on due to a lack of proper sleep can be quite serious and may contribute to significant changes in physical and psychological wellbeing and may, in fact, contribute to early mortality.
Cardiovascular Disorders — Several key studies in recent years have suggested a strong link between sleep deprivation and cardiovascular disorders, the number one cause of death in the United States. A group of researchers who were exploring such a link concluded that “treating sleep disorders may conceivably have a major impact on improvements in cardiovascular morbidity in the population.” Another study demonstrated that insomnia, in particular, was a major contributor to stroke, especially in younger men who may be dismissive of their symptoms.
Type 2 Diabetes — Studies have also noted links between sleep issues and type 2 diabetes, which is of particular interest since we have seen a substantial rise in the number of people diagnosed with this degenerative condition over the past decade. Several studies have noted significant changes in glucose metabolism and insulin resistance, as well as an increased risk of type 2 diabetes, in participants who were deprived of deep sleep, also known as slow wave sleep (SWS). Convincing data suggest that there is a strong correlation between a lack of SWS and insulin resistance. In addition, it has been found that changes in glucose metabolism during sleep and throughout the day also greatly affect the activities of two hormones, leptin, and ghrelin, which are regulated during sleep. When we receive proper sleep, leptin levels rise, reducing the desire to eat. The body hence shifts into a restoration state, conserving and building up its resources. On the other hand, when sleep-deprived, the leptin drop coincides with an increase in ghrelin levels, causing us to look for carbohydrates and salty foods during the day to increase much-needed adaptive energy. If the situation is prolonged, it will inevitably result in weight gain and potentially contribute to the onset of type 2 diabetes. Again we see that sleep is a major contributor to another chronic, degenerative, and costly medical disorder. So on those days when you can’t seem to eat enough carbs, and healthy food does not seem very appealing, consider whether or not you had enough quality sleep the night before.
Memory and Information Processing — Although REM sleep has been associated with dreaming, we now know that this stage of sleep plays a significant role in memory and information processing. Loss of sleep, especially REM sleep, can significantly impact simple recall and concentration. A fascinating study that was published a little over a year ago in the Journal of Science reported that perhaps one of the functions of sleep, especially REM sleep, is to provide the brain with a “neuronal shower,” whose very purpose is to remove neurotoxins from the central nervous systems. Amyloid plaques, in particular, are removed during this process, resulting in improved neuronal functioning, especially related to memory.
Depression — Excessive REM sleep regularly has been observed in patients who may be suffering from major depression. One explanation for this phenomenon has to do with the intense emotional processing that takes place during REM sleep. If the emotional processing is excessive and prolonged without the proper shift that occurs during the different stages of sleep, we may end up experiencing physical and mental exhaustion. Those who often report “dreaming the entire night” may also notice that they are more tired than usual upon waking as if they did not sleep at all. It is interesting to note that most antidepressant medications tend to reduce REM activity, moving it toward normal levels, and by doing so, among other things, they tend to improve physical and mental functioning. Is it improper sleep that contributes to depression or is it depression that causes poor sleep? While this question cannot be easily answered, based on years of empirical research, we know well that changes in sleep patterns act as a predictor of depressive illness. Once again, there is so much more to sleep!
Decision-Making and Impulse Control — Effective decision-making and impulse control, for example, are also functions that are improved during sleep. So we see an increase in aggressive and impulsive behaviors after prolonged periods of sleep deprivation. The implications of such findings are truly far-reaching, as we are witnessing more aggressive tendencies, poor judgment, and poor decision-making in those who, either by choice or by necessity, do not experience the restorative benefits of the nightly slumber.
Beyond the physical and psychological health benefits of sleep, there are even more fascinating areas that we have been exploring in our laboratories. For example, is there a relationship between sleep and creativity? At least 2 Nobel prize winners credited their success to dreams that either directed the researcher to approach the problem from a different perspective or actually provided the answer. German Nobel laureate, Otto Loewi, who made a significant contribution to our understanding of the chemical transmission of nerve impulses, explained the significance of his dream as follows:
The night before Easter Sunday of that year, I awoke, turned on the light, and jotted down a few notes on a tiny slip of paper. Then I fell asleep again. It occurred to me at 6 o’clock in the morning that I had written down something most important during the night, but I could not decipher the scrawl. The next night, at 3 o’clock, the idea returned. It was the design of an experiment to determine whether or not the hypothesis of chemical transmission that I had uttered 17 years ago was correct. I got up immediately, went to the laboratory, and performed a single experiment… according to the nocturnal design.
While many have suggested a tenuous connection between sleep and creativity, based on anecdotal, subjective data, we now have some convincing objective data that suggest that certain sleep stages can promote creativity and enhance problem-solving. One study, in particular, found a significant improvement in creativity when the participants were allowed to experience sufficient REM sleep, while those who slept but were deprived of REM sleep did not show such improvements. The study also showed that one of the key aspects of tapping into this creative process was exposure to a certain problem and even struggling with it before falling asleep. It appears that those aspects of our consciousness that may be resistant to viewing a problem from another perspective (thinking “outside the box”) tend to become inactive during REM sleep, hence allowing other perspectives and solutions to unveil themselves. In other words, during this stage, the part of us that says “No, it can’t be done” is out of the picture, while the parts that are capable of considering other possibilities are hard at work, especially while we dream.
While it is beyond the scope of this brief article to explore various methods of sleep restoration at any length, we can highlight several key points here:
First and foremost, several medical conditions can contribute to changes in sleep patterns, cause insomnia, or even excessive sleep. These need to be ruled out, and the person who can help is the family physician. Once medical and physical contributors have been ruled out, then other behavioral and cognitive interventions can be explored.
For decades, we have known that one major contributor to disrupted or insufficient sleep is excessive thinking, most notably worry, anxiety, or fear of the unknown (what may or could happen). In this same vein, we may also think too much about what happened in the past, hence ruminating about past experiences, especially emotionally laden experiences. Thinking keeps us up, wakes us up, and cheats us on the beneficial aspects of sleep. Therefore, mind-quieting techniques and approaches (for example, relaxation, prayer, and meditation) should be at the forefront of our treatment methods.
Many sleep disorders can be improved with proper sleep hygiene, such as by keeping a regular schedule for going to bed and waking up. A regular sleep schedule by itself can significantly improve sleep quality. Finally, what we eat or drink and what we do before falling asleep can potentially interfere with proper sleep. Stimulants and alcohol can have an adverse impact on initiating and maintaining sleep, while exercising late at night may keep us awake.
Sleep is a most complex, multifaceted, mysterious, and fascinating phenomenon with many properties that we are yet to discover. But above all, it is so critical to our health, performance, and creativity that we should not take it for granted.
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A noticeable decrease in physical energy
Diminished motivation
Increased sensitivity to pain
Cognitive changes (that is, in memory and concentration)
Loss of efficiency
Difficulty with attentiveness and staying on task
Breakdown in judgment
Tendency to become negative, aggressive, cynical, dysphonic
Weight gain
Sensitivity to fluctuations in ambient temperature
REFERENCES
Buxton OM, Pavlova M, Reid EW, Wang W, Simonson DC, Adler GK. Sleep restriction for 1 week reduces insulin sensitivity in healthy men. Diabetes. 2010;159:2126–2133.
Cai DJ, Mednick SA, Harrison EM, Kanady JC, Mednick SC. REM, not incubation, improves creativity by priming associative networks. Proc Natl Acad Sci U S A. 2009;106:10130–10134.
Tasali T, Leproult R, Ehrmann DA, Van Cauter E. Slow-wave sleep and the risk of type 2 diabetes in humans. Proc Natl Acad Sci U S A. 2008;105:1044–1049.
Wolk, R. Gami AS, Garcia-Touchard A, Somers VK. Sleep and cardiovascular disease. Curr Probl Cardiol. 2005;30:625–662.
Wu M-P, Lin H-J, Weng S-F, Ho C-H, Wang J-J, Hsu Y-W. Insomnia subtypes and the subsequent risks of stroke: Report from a nationally representative cohort. Stroke. 2014;45:1–6.
Zoccola PM, Dickerson SS. Assessing the relationship between rumination and cortisol: A review. J Psychosom Res. 2012;73:1–9.
Xie L, Kang H, Xu Q, et al. Sleep drives metabolite clearance from the adult brain. Science. 2013;342:373–377.
Dr. Micah Sadigh is a professor of psychology at Cedar Crest College in Allentown, Pennsylvania. Several of his publications address the treatment of dyssomnias and parasomnias. He may be reached at micasa@cedarcrest.edu