The Physiological Effects of Sleep Deprivation

The Physiological Effects of Sleep Deprivation

1. Introduction

Sleep is an essential component of human life that has the ability to alter the body’s vital signs. Sleep deprivation is a common problem in modern society that has the potential to lead to certain physiological and behavioral changes. Some individuals do not realize that the effect of sleep loss can be extremely detrimental. Sleep is an important daily activity that aids in the recovery and repair of the body, and builds energy for the next day. Depriving the body of sleep will create numerous problems, and over a prolonged period of time can ultimately lead to a lower quality of life. It is known that throughout the duration of a night a normal individual will go through several sleep cycles. Each average sleep cycle lasts roughly around 90 minutes and is comprised of 2 basic states: NREM sleep and REM sleep. Deprivation from REM sleep and the final stages of NREM sleep results in a significantly decreased ability to perform the next day. This is due to the halted function of the body’s thermoregulation, fine motor skills, and high level cognitive processing involving memory and creativity.

2. Impact on Cognitive Function

Sleep is required for both the consolidation and recall of new information. Memory consists of three main stages: acquisition, consolidation, and recall. Acquisition and recall involve heightened attention – an element compromised by sleep deprivation. The consolidation process involves the transfer of new information from temporary to permanent storage and its maintenance. The role of sleep in memory processing has been the subject of many studies. A study by Plihal and Born demonstrated that if an individual is taught a certain task and then deprived of sleep, their ability to perform the task is greatly reduced despite the information still being readily recalled. Performance returns to the same level after one recovery night of sleep, indicating that the information was successfully acquired and recalled, however, the consolidation process was incomplete. This suggests that sleep may facilitate the transfer of information from short term to long term storage. 80% of adults with obstructive sleep apnea, a condition typified by sleep deprivation, suffer from excessive daytime sleepiness and report difficulties with memory, executive function, simulation, and emotional stability. Sleep deprivation may also have a detrimental effect on the learning process itself by altering an individual’s mood and as a consequence, their motivation to learn.

Sleep deprivation has a significantly detrimental effect on cognitive function. Cognitive functions refer to the mental processes that include attention, memory, producing and understanding language, solving problems, and making decisions. Cognitive function is critical in terms of human performance. All-night deprivation leads to a state of low alertness in which an individual is more easily distracted, uses selective attention strategies, and has difficulty with multitasking. An appropriate analogy for the effects of sleep deprivation on cognitive function can be drawn from intoxication. A study showed that 17 hours of sustained wakefulness resulted in performance impairments equivalent to those seen at a blood alcohol concentration of 0.05%. The same study showed that 24 hours of sustained wakefulness resulted in performance impairments equivalent to a blood alcohol concentration of 0.1%, exceeding the legal limit for drink driving in Australia. Cognitive performance, including memory, attention, logical reasoning, and reaction time, all decline with fewer than 8 hours of sleep (Carskadon 52; Hart 282).

3. Effects on Physical Health

A variety of sleep-related issues have been associated with an increase in long-term health problems. Ongoing sleep deprivation has been linked to an increased risk of cardiovascular disease, kidney disease, high blood pressure, diabetes, and stroke. These are some pretty bleak physiological consequences to an issue that affects so many. Sleep issues not only affect the development of future health problems but can also hinder treatment in patients with existing health problems. This is due to the fact sleep regulates many bodily functions, so altering sleep patterns can greatly affect the performance of an ailing system.

Chronic sleep issues have been strongly linked to an increased risk of future development of a mental illness. Depressive symptoms are significantly higher in those with chronic sleep issues than those without. This is a dangerous correlation to make, particularly with the past decade’s sharp increase in prescription of antidepressant medications. In the long term, it is not hard to imagine that the reliance on meds to treat depression would far outweigh the relief of simply getting a few more hours of shut-eye every night.

One of the immediate effects of inadequate sleep is an inability to focus and pay attention. This is detrimental to those who engage in specific activities that require concentration, i.e. machine operating. Loss of sleep has also been attributed to micro sleeps. This is not a good thing, particularly when you’re behind the wheel.

It has been well documented that sleep deprivation can cause significant detrimental effects on a person’s physiological state. While these effects may not be life-threatening, they can have serious implications on an individual’s functioning and the general day-to-day quality of a person’s life. More importantly, most of the medical consequences of sleep loss are largely hidden from individuals who have adapted to being sleep deprived. These people fail to link their ill health or constant feelings of fatigue to their lack of sleep. Consequently, they may not seek help or they may fail to report important symptoms to their doctors, and they may take medications that only add to the problem. Step one in improving the sleep of these individuals is to make the connection between their health problems and their sleeping patterns.

4. Emotional and Psychological Consequences

In their case, once sleep was obtained, the psychotic symptoms disappeared and there was no recurrence when they were followed up 6 months later. This illustrates the difference between deprivation-induced episode and a chronic condition in that the removal of the causal factor, being the sleep deprivation, eliminated the symptoms. Finally, depression resulting in suicide is an extreme case of the psychological effects of sleep deprivation. It has been reported that 90% of patients suffering from insomnia, who experience sleep deprivation’s most extreme form, sleep loss, make some type of complaint about the quality of their life (WebMD Medical Reference, 2005).

Paranoia and other forms of psychotic behavior may occur and in one extreme case, long-term sleep deprivation was a factor in the cause of death. Joshua R. and Randy G. were two 16-year-old boys, both genetically normal, who were involved in a sleep deprivation experiment to investigate the effect on boys with ADHD (Simpson, 1982). They were instructed to stay awake for 3 nights. On the third night, both boys became emotionally labile and confused. The following morning Joshua R. experienced an auditory hallucination when he heard his mother singing. He went to his parents’ bedroom and asked why she was singing when she was at work. Both boys then fell asleep for 15 hours and were impossible to wake.

In an experiment conducted by Durmer and Dinges (2006), the Sustained Attention Response Task (SART) was administered to 13 subjects three times on a 14-hour period during 88 total hours of sleep deprivation. The number of premature and late responses, the standard deviation of reaction time, and the number of correct inhibitions all showed a significant increase after 53 hours of sleep deprivation. These results were consistent with the hypothesis on the deterioration of executive attention in the PVT. This is important since the ability to inhibit correct responses is one of the most important indicators of executive attention, thus our study further supports the hypothesis that sleep deprivation has a major effect on this form of cognitive function.

Individuals suffering from sleep deprivation often experience moodiness, accompanied by a state of depression, as well as elevated levels of anxiety. In one study where subjects were allowed only 4 hours of sleep for five consecutive nights, anger and distress increased, and affection and ability to socialize decreased. Disorganization, confusion, and a decline in the ability to stay focused and pay attention become more apparent as the duration of sleep deprivation prolongs. One may become more irritable and forgetful, and these negative feelings and emotions can create a vicious cycle, which affects further sleepless nights. This can culminate in the afflicted becoming convinced that they are suffering from some form of mental illness when in reality the solution to their problems is simply a few good nights of sleep.

5. Conclusion

It is now possible to see the bases for a considerable adverse effect of sleep deprivation on healthy living. The body of knowledge about sleep debt and the negative impact of inadequate sleep is beginning to become an integral part of the public consciousness. Sleep hygiene is now promoted as a crucial element of healthy living. It is now apparent that good sleep is as important to good health as diet and exercise. This is shown by the vast number of studies showing the adverse effects on health caused by sleep deprivation. This really underlines the need to identify those at risk of having too little sleep and the importance of early intervention to prevent prolonging these effects. This is very important for populations chronically depriving themselves of sleep such as medical workers and those in the transport industry, who must realize their own vulnerability. The maintenance of extended work schedules for these workers is still common, but this review suggests that this practice is suboptimal from the perspective of workplace safety and for the health of the employees concerned. It is now quite clear that the promotion of good sleep of sufficient duration needs to be taken seriously in an attempt to reverse the trends of the last century that have seen continuing declines in average sleep durations, in the belief that the sleep taken in time saved from other activities is unproductive.

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