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تاريخ التسجيل : 18/07/2010
|موضوع: Insomnia 5/9/2010, 12:21|| |
Insomnia is a symptomthat can accompany several sleep, medical and psychiatric disorders, characterized by persistent difficulty falling asleep and/or difficulty staying asleep. Insomnia is typically followed by functional impairment while awake.
Both organic and non-organic insomnia without other cause constitute a sleep disorder, primary insomnia. One definition of insomnia is "difficulties initiating and/or maintaining sleep, or nonrestorative sleep, associated with impairments of daytime functioning or marked distress for more than 1 month."[
Types of insomnia
Although there are several different degrees of insomnia, three types of insomnia have been clearly identified: transient, acute, and chronic.
1. Transient insomnia lasts for less than a week. It can be caused by another disorder, by changes in the sleep environment, by the timing of sleep, severe depression, or by stress. Its consequences - sleepiness and impaired psychomotor performance - are similar to those of sleep deprivation.
2. Acute insomnia is the inability to consistently sleep well for a period of less than a month.
3. Chronic insomnia lasts for longer than a month. It can be caused by another disorder, or it can be a primary disorder. Its effects can vary according to its causes. They might include being unable to sleep, muscular fatigue, hallucinations, and/or mental fatigue; but people with chronic insomnia often show increased alertness. Some people that live with this disorder see things as if they are happening in slow motion, wherein moving objects seem to blend together. Can cause double vision
Insomnia can be caused by:
• Psychoactive drugs or stimulants, including certain medications, herbs, caffeine, nicotine, cocaine, amphetamines, methylphenidate, MDMA and modafinil
• Fluoroquinolone antibiotic drugs, see Fluoroquinolone toxicity, associated with more severe and chronic types of insomnia
• Restless Legs Syndrome can cause insomnia due to the discomforting sensations felt and need to move the legs or other body parts to relieve these sensations. It is difficult if not impossible to fall asleep while moving.
• PainAny injury or condition that causes pain. Pain can preclude an individual from finding a comfortable position in which to fall asleep, and in addition can cause awakening if, during sleep, the person rolls over and puts pressure on the injured or painful area of the body.
• Hormone shifts such as those that precede menstruation and those during menopause
• Life problems like fear, stress, anxiety, emotional or mental tension, work problems, financial stress.
• Mental disorders such as bipolar disorder, clinical depression, generalized anxiety disorder, post traumatic stress disorder, schizophrenia, or obsessive compulsive disorder.
• Disturbances of the circadian rhythm, such as shift work and jet lag, can cause an inability to sleep at some times of the day and excessive sleepiness at other times of the day. Jet lag is seen in people who travel through multiple time zones, as the time relative to the rising and setting of the sun no longer coincides with the body's internal concept of it. The insomnia experienced by shift workers is also a circadian rhythm sleep disorder.
• Certain neurological disorders, brain lesions, or a history of traumatic brain injury
• Medical conditions such as hyperthyroidism and rheumatoid arthritis
• Abuse of over-the counter or prescription sleep aids can produce rebound insomnia
• Poor sleep hygiene, e.g., noise
• Parasomnia, which includes a number of disruptive sleep events including nightmares, sleepwalking, night terrors, violent behavior while sleeping, and REM behavior disorder, in which a person moves his/her physical body in response to events within his/her dreams
• A rare genetic condition can cause a prion-based, permanent and eventually fatal form of insomnia called fatal familial insomnia.
• Physical exercise. Exercise-induced insomnia is common in athletes, causing prolonged sleep onset latency.
Treatment for insomnia
The most commonly used class of hypnotics prescribed for insomnia are the benzodiazepines. Benzodiazepines bind unselectively to the GABAA receptor. These include drugs such as temazepam, flunitrazepam, triazolam, flurazepam, midazolam, nitrazepam and quazepam. These drugs can lead to tolerance, physical dependence and the benzodiazepine withdrawal syndrome upon discontinuation, especially after consistent usage over long periods of time. Benzodiazepines while inducing unconsciousness, actually worsen sleep as they promote light sleep whilst decreasing time spent in deep sleep such as REM sleep. A further problem is with regular use of short acting sleep aids for insomnia, day time rebound anxiety can emerge. Benzodiazepines can help to initiate sleep and increase sleep time but they also decrease deep sleep and increase light sleep. Although there is little evidence for benefit of benzodiazepines in insomnia and evidence of major harm prescriptions have continued to increase. There is a general awareness that long-term use of benzodiazepines for insomnia in most people is inappropriate and that a gradual withdrawal is usually beneficial due to the adverse effects associated with the long-term use of benzodiazepines and is recommended whenever possible.
Nonbenzodiazepine sedative-hypnotic drugs, such as zolpidem, zaleplon, zopiclone and eszopiclone, are a newer classification of hypnotic medications. They work on the benzodiazepine site on the GABAA receptor complex similarly to the benzodiazepine class of drugs. Some but not all of the nonbenzodiazepines are selective for the α1 subunit on GABAA receptors which is responsible for inducing sleep and may therefore have a cleaner side effect profile than the older benzodiazepines. Zopiclone and eszopiclone like benzodiazepine drugs bind unselectively to α1, α2, α3 and α5 GABAA benzodiazepine receptors. Zolpidem is more selective and zaleplon is highly selective for the α1 subunit, thus giving them an advantage over benzodiazepines in terms of sleep architecture and a reduction in side effects. However, there are controversies over whether these non-benzodiazepine drugs are superior to benzodiazepines. These drugs appear to cause both psychological dependence and physical dependence though less than traditional benzodiazepines and can also cause the same memory and cognitive disturbances along with morning sedation.
Alcohol is often used as a form of self-treatment of insomnia to induce sleep. However, alcohol use to induce sleep can be a cause of insomnia. Long-term use of alcohol is associated with a decrease in NREM stage 3 and 4 sleep as well as suppression of REM sleep and REM sleep fragmentation. Frequent moving between sleep stages occurs, with awakenings due to headaches, polyuria, dehydration and diaphoresis. Glutamine rebound also plays a role as when someone is drinking, alcohol inhibits glutamine, one of the body's natural stimulants. When the person stops drinking, the body tries to make up for lost time by producing more glutamine than it needs. The increase in glutamine levels stimulates the brain while the drinker is trying to sleep, keeping them from reaching the deepest levels of sleep. Stopping chronic alcohol use can also lead to severe insomnia with vivid dreams. During withdrawal REM sleep is typically exaggerated as part of a rebound effect.
Opioid medications such as hydrocodone, oxycodone, and morphine are used for insomnia which is associated with pain due to their analgesic properties and hypnotic effects. Opioids can fragment sleep and decrease REM and stage 2 sleep. By producing analgesia and sedation, opioids may be appropriate in carefully selected patients with pain-associated insomnia.
Some antidepressants such as amitriptyline, doxepin, mirtazapine, and trazodone can often have a very strong sedative effect, and are prescribed off label to treat insomnia. The major drawback of these drugs is that they have properties which can lead to many side effects, for example; amitriptyline and doxepin both have antihistaminergic, anticholinergic and antiadrenergic properties which contribute to their side effect profile, while mirtazapines side effects are primarily antihistaminergic, and trazadones side effects are primarily antiadrenergic. Some also alter sleep architecture. As with benzodiazepines, the use of antidepressants in the treatment of insomnia can lead to withdrawal effects; withdrawal may induce rebound insomnia.
Mirtazapine is known to decrease sleep latency, promoting sleep efficiency and increasing the total amount of sleeping time in patients suffering from both depression and insomnia.
Melatonin and melatonin agonists
The hormone and supplement melatonin is effective in several types of insomnia. Melatonin has demonstrated effectiveness equivalent to the prescription sleeping tablet zopiclone in inducing sleep and regulating the sleep/waking cycle. One particular benefit of melatonin is that it can treat insomnia without altering the sleep pattern which is altered by many prescription sleeping tablets. Another benefit is it does not impair performance related skills.
Melatonin agonists, including ramelteon (Rozerem) and tasimelteon, seem to lack the potential for misuse and dependence. This class of drugs has a relatively mild side effect profile and lower likelihood of causing morning sedation. While these drugs show good effects for the treatment of insomnia due to jet lag, the results for other forms of insomnia are less promising.
Natural substances such as 5-HTP and L-Tryptophan have been said to fortify the serotonin-melatonin pathway and aid people with various sleep disorders including insomnia.
The antihistamine diphenhydramine is widely used in nonprescription sleep aids such as Benadryl. The antihistamine doxylamine is used in nonprescription sleep aids such as Unisom (USA) and Unisom 2 (Canada). In some countries, including Australia, it is marketed under the names Restavit and Dozile. It is the most effective over-the-counter sedative currently available in the United States, and is more sedating than some prescription hypnotics
While the two drugs mentioned above are available over the counter in most countries, the effectiveness of these agents may decrease over time and the incidence of next-day sedation is higher than for most of the newer prescription drugs. Anticholinergic side effects may also be a draw back of these particular drugs. Dependence does not seem to be an issue with this class of drugs.
Cyproheptadine is a useful alternative to benzodiazepine hypnotics in the treatment of insomnia. Cyproheptadine may be superior to benzodiazepines in the treatment of insomnia because cyproheptadine enhances sleep quality and quantity whereas benzodiazepines tend to decrease sleep quality.
Low doses of certain atypical antipsychotics such as quetiapine, olanzapine and risperidone are also prescribed for their sedative effect but the danger of neurological, metabolic and cognitive side effects make these drugs a poor choice to treat insomnia. Over time, quetiapine may lose its effectiveness as a sedative. The ability of quetiapine to produce sedation is determined by the dosage. Higher doses (300 mg - 900 mg) are usually taken for its use as an antipsychotic, while lower doses (25 mg - 200 mg) have a marked sedative effect, e.g. if a patient takes 300 mg, he/she will more likely benefit from the drug's antipsychotic effects, but if the dose is brought down to 100 mg, it will leave the patient feeling more sedated than at 300 mg, because it primarily works as a sedative at lower doses.
Eplivanserin is an investigational drug with a mechanism similar to these antipsychotics, but probably with less side effects.
Some insomniacs use herbs such as valerian, chamomile, lavender, hops, and passion-flower. Valerian has undergone multiple studies and appears to be modestly effective.
Insomnia may be a symptom of magnesium deficiency, or low magnesium levels, but this has not yet been proven. A healthy diet containing magnesium can help to improve sleep in individuals without an adequate intake of magnesium.