Search:
 
 
   
  Sleep Disorders See Related Products
Previous | Page of 2 )

Sleep and Wakefulness

Overview

Sleep Disorders Sleepwhich is defined behaviorally by the normal suspension of consciousness and electrophysiologically by specific brain wave criteriaconsumes fully a third of our lives. Sleep occurs in all mammals, and probably all vertebrates. We crave sleep when deprived of it, and, to judge from animal studies, continued sleep deprivation can ultimately be fatal. Surprisingly, however, this peculiar state is not the result of a simple diminution of brain activity; rather, sleep is a series of precisely controlled brain states, and in some of these the brain is as active as it is when people are awake. The sequence of sleep states is governed by a group of brainstem nuclei that project widely throughout the brain and spinal cord. The reason for high levels of brain activity during some phases of sleep, the significance of dreaming, and the basis of the restorative effect of sleep are all topics that remain poorly understood. The clinical importance of sleep is obvious from the prevalence of sleep disorders (insomnias). Each year about 40 million Americans suffer from chronic sleep disorders and an additional 20 million experience occasional sleeping problems.

Sleep Disorders

An estimated 20% of the U.S. population experience during their lifetime some kind of sleep disorder. These problems range from simply annoying to life threatening. The most common problems are insomnia, sleep apnea, "restless legs" syndrome, and narcolepsy.

Insomnia, or the inability to sleep, has many causes. Short-term insomnia can arise from stress, jet lag, or simply drinking too much coffee. These problems can usually be prevented by improving sleep habits, avoiding stimulants like caffeine at night, and in some cases taking sleep-promoting medications. More serious insomnia is associated with psychiatric disorders such as depression that presumably affect the balance between the cholinergic, adrenergic, and serotinergic systems that control the onset and duration of the sleep cycles. Long-term insomnia is a particular problem in the elderly because they sleep less, are subject to more depression, and frequently take medications that affect the relevant neurotransmitter systems.

Sleep apnea refers to interrupted breathing during sleep that affects about 18 million Americans, most often obese males in middle age. A person suffering from sleep apnea may awaken hundreds of times during the night, with the result that they have little or no slow-wave sleep and spend less time in REM sleep. Consequently, these individuals are chronically tired in the daytime and often suffer from depression that exacerbates the problem. In some high-risk individuals, sleep apnea may even lead to sudden death from respiratory arrest during sleep. The underlying problem is that the airway collapses during breathing, thus blocking air flow. In normal sleep, breathing slows and muscle tone decreases throughout the body, including the tone of the pharynx. If the brainstem circuitry regulating commands to the chest wall or to pharyngeal muscles is affected, or if the airway is compressed because of the weight on it during sleep, the pharynx tends to collapse as the muscles relax during breathing. As a result, oxygen levels decrease and the ensuing reflex to inspire more air awakens people suffering from this disorder.

A third sleep disorder is "restless legs syndrome," a familial disorder causing unpleasant crawling, prickling, or tingling sensations in the legs and feet, and an urge to move them about for relief. This problem is surprisingly common, affecting about 12 million (mostly elderly) Americans. The result is constant leg movement during the day and fragmented sleep patterns at night. The neurobiology of this particular problem is not understood, but the problem often can be relieved by drugs that inhibit the release of dopamine.

The sleep disorder that is best understood in neurobiological terms is narcolepsy, a chronic disorder that affects about 250,000 people in the United States. Individuals with narcolepsy have frequent "REM sleep attacks" during the day, in which they enter REM sleep from wakefulness without going through non-REM sleep. Such individuals may become cataplectic during these episodes, and can fall down (cataplexy refers to a temporary loss of muscle control). Insight into the causes of narcolepsy have come from studies of dogs suffering from a genetic disorder similar to the human disease. In these animals, narcolepsy is caused by a mutation of the hypocretin receptor 2 gene (Hcrtr2). Hypocretins (or orexins) are neuropeptides homologous to secretin, which is found exclusively in cells in the tuberal region of the hypothalamus. These hypothalamic cells project to the reticular formation, the locus coeruleus and the dorsal raphe nucleus, all of which control various aspects of sleep. The evidence in dogs suggests that the Hcrtr2 mutation cause a hyperexcitability of the neurons that generate REM sleep, and/or impairment of the circuits that inhibit REM sleep

Previous | Page of 2 )
 

Top Selling Health Products:

A high percentage of radioactive fallout is in the form of radioactive iodine. Potassium iodide provides enough safe iodine to completely fill the thyroid's binding sites, blocking any radioactive iodine from binding there.
Potassium Iodide, 14 tablets (BBA-LEF-00577)
  $5.21  View More
  
In more than 2,000 published studies, DHEA has been shown to have a role in improving neurological function, immune function, stress disorders, hormonal modulation and numerous diseases associated with normal aging.
Life Extension, DHEA, 25 Mg, 100 Capsules (LEF-00335) [free shipping*]
  $12.00  View More
  
SAMe (S-Adenosyl-Methionine) 400 mg, 30 enteric coated tablets
Life Extension, SAMe (S-Adenosyl-Methionine) 400 mg, 30 enteric coated tablets (LEF-01933) [free shipping*]
  $27.00  View More
  
Taurine is a conditionally essential amino acid produced from cysteine by the body and found abundantly in the body, particularly throughout the excitable tissues of the central nervous system, where it is thought to have a regulating influence.
Life Extension, Taurine Capsules, 90 Veggie Capsules (LEF-00199) [free shipping*]
  $13.00  View More
  
L-cysteine is a conditionally essential amino acid, one of only three sulfur-containing amino acids. L-cysteine can act as an antioxidant, may prevent liver diseases, and can help to thicken the individual diameters of existing hair.
Life Extension, Mega L Glutathione Capsules, 250 mg, 60 capsules (LEF-00314) [free shipping*]
  $31.00  View More
  
FLORASSIST® Mood-60 capsules
Life Extension, FLORASSIST® Mood-60 capsules (LEF-02000) [free shipping*]
  $26.75  View More
  
Pregnenolone, 50 mg 100 capsules
Life Extension, Pregnenolone, 50 mg 100 capsules (LEF-00302) [free shipping*]
  $19.50  View More
  
L-phenylalanine is an essential amino acid which can be converted to L-tyrosine by a complex biochemical process which takes place in the liver. L-tyrosine can be converted by neurons in the brain to dopamine and norepinephrine hormones.
Life Extension, Tyrosine, 500 mg, 100 tablets (LEF-00326) [free shipping*]
  $11.00  View More
  
In more than 2,000 published studies, DHEA has been shown to have a role in improving neurological function, immune function, stress disorders, hormonal modulation and numerous diseases associated with normal aging.
Life Extension, DHEA, 15 Mg 100 Capsules (LEF-00454) [free shipping*]
  $10.50  View More
  
As a supplement, glucosamine comes in several different forms of which the sulfated, hydrochloric acid, and N-acetylated are commonly available. Chondroitin sulfates provide the structural components of joint cartilage, inhibit free radical enzymes.
Life Extension, Glucosamine/Chondroitin Sulfate, 100 capsules (LEF-00522) [free shipping*]
  $28.50  View More
  
   

Related Categories

To maintain good health we must take the correct nutritional supplements so that our body has a chance to protect and heal itself. Select the health condition that concerns you from the list below and you will find a list of carefully selected products

Chronic Fatigue SyndromeDepressionFatigue
HeadacheInsomniaRestless Legs
Sleep ApneaSnoring

Related Clinical Studies

Sunburn prevalence among adults in the United States, 1999.
Exposure to high levels of sunlight, such as a sunburn, is a strong determinant of melanoma risk. Of 156,354 adults aged > or =18 years, 31.7% (95% confidence interval, 31.3%-32.1%) reported a sunburn in the past year; of adults aged 18 to 29 years, 57.5% reported such a sunburn. Nationwide and statewide skin cancer prevention efforts should target young adults. Periodic monitoring of sunburn is important in evaluating the effectiveness of those efforts.
Read More  
posted 3/15/2004 7:23:41 PM

Dietary factors in the prevention and treatment of nonmelanoma skin cancer and melanoma.
Read More  
posted 3/15/2004 6:41:22 PM