Sleep Disorders | September 8, 2014 | Author: The Super Pharmacist
Sleepiness is caused by abnormal sleep quantity or sleep quality. Disorders characterised by hypersomnolence (sleepiness) during normal waking hours that may impair cognitive functioning include primary hypersomnia disorders (e.g., idiopathic hypersomnolence; narcolepsy; and Kleine-Levin Syndrome) and secondary hypersomnia disorders where excessive somnolence can be attributed to a known cause (e.g., drug affect, mental disorders, and sleep apnea syndrome). The International Classification of Sleep Disorders (ICSD) describes primary hypersomnia as an idiopathic disorder of presumed central nervous system cause that is associated with excessive sleepiness.
Primary hypersomnia is an idiopathic disorder, meaning it has no known cause.
Although head injury or viral infections can cause a disorder resembling primary hypersomnia, the true causes for most cases remain unknown. No genetic, environmental, or other predisposition has been identified. The predominant complaint is excessive sleepiness for at least one month (or less if recurrent), as evidenced by either prolonged sleep episodes or daytime sleep episodes that occur almost daily.
The excessive sleepiness causes clinically significant distress or impairment in social, occupational, or other important areas of functioning. The excessive sleepiness is not accounted for by insomnia, does not occur exclusively during the course of another mental disorder, and is not due to the direct physiologic effects of a substance (eg, drug of abuse, medication) or a general medical condition.
The true prevalence of primary hypersomnia in the general population is not known. Approximately 5%-10% of individuals who present to sleep disorder clinics with complaints of daytime sleepiness are diagnosed as having primary hypersomnia.
Several clinical forms of primary idiopathic hypersomnia have been described in the past. According to the most recent (fifth) edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) published in 2013, idiopathic hypersomnia is now divided into
Idiopathic hypersomnia with long sleep time is characterised by a major sleep episode that is at least 10 hours in duration, The hallmark of idiopathic hypersomnia with and without long sleep time is constant, severe excessive daytime somnolence. Those individuals with a long sleep time generally sleep around 12 to 14 hours per night (although a sleep time of greater than 10 hours is sufficient for this group) and may also nap for 3 to 4 hours through the day.
Those without a long sleep time may have a major sleep episode that is normal or slightly longer than that seen in normal individuals (but the duration is less than 10 hours); they may experience excessive sleepiness throughout the day with unintended naps that are typically unrefreshing.
Sleep fragmentation (interruption of sleep with frequent brief arousals) is not present in either group. They both struggle to awaken in the morning or at the end of their nap. Patients report sleep drunkenness, or confusion, on awakening. An alarm clock alone is usually insufficient to awaken these people.
Onset of this condition is most often during adolescence and rarely after the age of 30 years.
This is usually a life-long disease, although recent series suggest that hypersomnia may spontaneously disappear in 14–25% of patients.
A variant of the condition is called "recurrent" (recurrent hypersomnia or primary recurrent hypersomnia) when periods of excessive sleepiness last at least 3 days and occur several times a year for at least 2 years. In between these periods, patients do not have excessive daytime sleepiness.
The most well known type of recurrent hypersomnia is known as the Kleine-Levin’s syndrome. Kleine-Levin syndrome is a recurrent hypersomnia characterised by episodes of hypersomnia separated by intervening periods of normal behaviour. In addition to hypersomnia, at least one of the following symptoms must be present:
It is a disease predominantly of teenagers, and boys are four times more likely to be affected than girls.The other form of recurrent hypersomnia is menstrual-related hypersomnia and occurs in association with the menstrual cycle. Episodes usually last approximately one week and resolve at the time of menses.
It is not uncommon for idiopathic hypersomnia to be mistaken for narcolepsy. However, although patients with idiopathic hypersomnia present with excessive daytime sleepiness, they do not experience cataplexy (sudden attacks of muscle weakness ranging from head drooping to complete collapse which are diagnostic of narcolepsy), or significant nocturnal sleep disruption (fragmented nocturnal sleep and frequent nocturnal awakenings which are characteristic of narcolepsy). The abrupt sleep attacks seen in classic narcolepsy are not present in primary hypersomnia.
Patients with primary hypersomnia may become irritable or even abusive in response to the efforts of others to rouse them.
The primary difference between this and primary hypersomnia is that persons experiencing recurring hypersomnia will have extended periods where they do not exhibit any signs of hypersomnia, whereas persons experiencing primary hypersomnia are affected by it nearly all the time.
As with narcolepsy, other disorders producing excessive daytime sleepiness (such as insufficient sleep, sleep-related breathing disorders, and periodic limb movement disorders) must be ruled out before the diagnosis of idiopathic hypersomnia is made.
Polysomnography studies of patients with idiopathic hypersomnia usually reveal shortened initial sleep latency, increased total sleep time and normal sleep architecture (in contrast to narcoleptic patients, who exhibit significant sleep fragmentation).
Mean sleep latency in primary hypersomnia as measured on the Multiple Sleep Latency Test (MSLT) is usually reduced, often in the 8–10 minute range (the normal range being 15 to 20 minutes), but sometimes dramatically shorter. Also in contrast to narcolepsy, sleep onset rapid eye movement episodes (SOREMs), wherein the person goes into the dream phase or REM cycle soon after sleep onset, are not typically seen.
Severe idiopathic hypersomnia is a disabling problem that often leads to permanent unemployment with poor responses to medical treatment. Moreover, because the underlying cause of idiopathic hypersomnia is unknown, treatment remains symptomatic in nature. There are no treatments approved for idiopathic hypersomnia, although it is common practice to use wake-promoting medications that are known to be effective in patients with narcolepsy to treat the sleepiness associated with idiopathic hypersomnia.
Therapy for idiopathic hypersomnolence involves maintaining the patient on daily doses of stimulants. The drug dose is titrated so that the patient stays alert during the day, but adverse effects should be avoided.
Methylphenidate (Ritalin) and dextroamphetamine are the most commonly prescribed medications. Increased dopamine release is thought to be the mechanism of wake-promotion by these medications.
Modafinil (Modavigil) and armodafinil (Nuvigil) have proven clinically useful in the treatment of narcolepsy and other causes of excessive daytime sleepiness, such as idiopathic hypersomnolence.
These medications are psychostimulants that enhance wakefulness and vigilance, but their pharmacologic profile is notably different from the amphetamines, methylphenidate, or cocaine. Modafinil and armodafinil are less likely to produce side effects such as jitteriness, anxiety, or excess locomotor activity or to lead to a hypersomnolent rebound effect. They are long-acting; the normal elimination half-life of modafinil in humans is between 12-15 hours. These medicines may not work as well for primary hypersomnia as they do for narcolepsy.
Lifestyle changes can help ease symptoms and prevent injury
The treatment of recurrent primary hypersomnia with stimulant medication is usually only partially effective.Other drugs used to treat hypersomnia include clonidine, levodopa, bromocriptine, antidepressants, and monoamine oxidase inhibitors (MAOs).
Kleine-Levin syndrome has been reported to resolve occasionally by itself around middle age and menstrual-related recurrent hypersomnia is responsive to the use of birth control pills. With those exceptions, hypersomnia is considered both a lifelong disorder and one that can be significantly disabling. There is no body of evidence that defines successful treatment of the majority of hypersomnia cases.
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