Neurology, Neuromuscular Disorders,
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Extrinsic Sleep Disorders

EXTRINSIC SLEEP DISORDERS

INADEQUATE SLEEP HYGIENE AND ENVIRONMENTAL SLEEP DISORDERS

In 1939, Nathaniel Klietman wrote the pioneering chapter on sleep hygiene. In it, he outlined environmental and behavioral influences that affect sleep quality. Since then the importance of sleep hygiene has been the focus of increasing attention, as poor sleep habits and poor sleep environment factors have been identified as contributing to disrupted sleep. It is surprising how often sleep disturbances arise or are perpetuated by maladaptive behaviors or lack of consideration of the sleep environment (the bedroom). These factors are, for the most part, under the individual's control, and yet are often overlooked.

One behavioral factor is the timing and duration of sleep. The amount of sleep required by individuals is quite variable. It can range easily from 6 to 8 hours in young individuals. The individual usually has an "intuition" as to what is the appropriate amount of sleep. Sometimes, however, social obligations, work requirements, and recreational desires lead to the individual ignoring these sleep requirements and intentional sleep deprivation. Sleep restriction beyond the individual's needs results in daytime fatigue, poor performance, and mood swings. In addition, the body craves regularity of bedtime and arise time. Shifts of these times also lead to similar problems (see shift work sleep disorders). There is also an element of natural sleepiness, which occurs about 8 hours after the main sleep period. Napping more than 10 to 15 minutes at any time other than this peak can have adverse effects on the quality sleep during the next main sleep period.

Environmental sleep disorders arise when the main sleep environment is not conducive to good quality sleep. Here too, it is surprising how frequently there is little insight as to the nature of the offending factors. The ideal sleep environment should be quiet, dark, and comfortable. Extremes in temperature can affect the quality of sleep. The quality of the mattress can also affect sleep quality. It is true that individuals can adapt to a variety of environmental disturbances, such as the noise of city streets. Frequently, it is an abrupt change in the sleep environment that precipitates the sleep disturbance. New construction taking place outside, a move from the city to the country, are examples. In addition, when the bed or bedroom is used for other activities such as work or watching television, a learned association with the wakeful activity can take place leading to poor sleep quality.

INSUFFICIENT SLEEP SYNDROME 

As noted above, individuals requirements for sleep duration vary quite a bit. As a rule, people intuitively know how much sleep they require. Frequently, however, people ignore their internal clock in order to keep up with work requirements, school requirements, deadlines, social obligations and recreational activities. Work responsibilities have been rising considerably. The average annual work hours have increased by an entire month of full time work in the last 30 years. The average duration of sleep has decreased by 20% of the last 100 years. This is not due to physiologic changes in the human requirement for sleep but rather influenced by major industrial advances, primarily in availability of artificial light. Many individuals are sacrificing sleep for wakeful activities. Social stigma associates sleep and sleepiness with laziness and lack of productivity. The result is a sleep deprived society with all the consequences, including inattentiveness, irritability, poor productivity, and increased risk of industrial and motor vehicle accidents.

HYPNOTIC, STIMULAND AND ALCOHOL DEPENDENT SLEEP DISORDERS 

Alcohol has been used for centuries for help in inducing sleep. The so called "night cap" has many a time been the resort sought by individuals with difficulty sleeping. While alcohol does have sedating properties, paradoxically, as the alcohol is eliminated from the body, there is an activating effect on the brain. The individual gets sleepy enough to induce sleep, but the sleep quality is disrupted several hours later as the alcohol leaves the body. People also turn to other drugs for sleep induction, both prescription and non-prescription. Of the $16 billion in direct medical costs to the American public for sleep disorders annually, the majority was spent on pharmaceutical intervention. Many of these drugs when used chronically have a propensity to cause a sleep dependence. In other words, after long term use, when the individual tries to stop using the drug there is a rebound insomnia which many times is worse than the insomnia which was originally being treated. Many of these drugs remain in the body for long periods. The direct effects of these drugs on daytime performance are only now being addressed by medical science. Meanwhile, the individuals taking these medications are engaging in normal unrestricted activities in the workforce.

Caffeine is likely the most common stimulant used in today's society. Both in dietary sources such as coffee and sodas, and in over-the-counter pill form, many individuals are self-medicating in order to counteract their sleepiness. Still more individuals are under the influence of prescription stimulants both for mood and to stay alert and as diet pills. In addition there is an active black-market supply of stimulant street drugs. These drugs produce increases in nocturnal awakenings and reduced nocturnal sleep time resulting in a decrease in the restorative effects of sleep. This ends up in a vicious cycle of continued stimulant ingestion to combat the daytime fatigue.

Nicotine also deserves mention here. At low blood concentrations, nicotine can have a relaxing and sedating effect. At higher concentrations, nicotine has stimulating effects similar to caffeine. Heavy smokers often smoke just before bedtime. If troubled with insomnia, they will often get up and smoke during the night as well, adding further to a physiologic disruption of their sleep quality.