Hypersomnia
Hypersomnia
Definition
Hypersomnia refers to a set of related disorders that involve excessive daytime sleepiness.
Description
There are two main categories of hypersomnia: primary hypersomnia (sometimes called idiopathic hypersomnia) and recurrent hypersomnia (sometimes called recurrent primary hypersomnia). Both are characterized by the same signs and symptoms and differ only in the frequency and regularity with which the symptoms occur.
Primary hypersomnia is characterized by excessive daytime sleepiness over a long period of time. The symptoms are present all, or nearly all, of the time. Recurring hypersomnia involves periods of excessive daytime sleepiness that can last from one to many days and recur over the course of a year or more. The main difference between this and primary hypersomnia is that persons experiencing recurring hypersomnia will have prolonged periods where they do not exhibit any signs of hypersomnia, whereas persons experiencing primary hypersomnia are affected by it nearly all the time. One of the best documented forms of recurrent hypersomnia is Kleine-Levin syndrome , although there are other forms as well.
There are many different causes for daytime sleepiness that are not considered hypersomnia, and there are many diseases and disorders in which excessive daytime sleepiness is a primary or secondary symptom. Feelings of daytime sleepiness are often associated with the use of common substances such as caffeine, alcohol, and many medications. Other common factors that can lead to excessive daytime sleepiness that is not considered hypersomnia include shift work and insomnia. Shift work can disrupt the body’s natural sleep rhythms. Insomnia can cause excessive daytime sleepiness because of lack of nighttime sleep and is a separate disorder.
Causes and symptoms
People experiencing hypersomnia do not get abnormal amounts of nighttime sleep. However, they often have problems waking up in the morning and staying awake during the day. People with hypersomnia nap frequently and do not feel refreshed upon waking from the naps. Hypersomnia is sometimes misdiagnosed as narcolepsy. In many ways the two are similar. One significant difference is that people with narcolepsy experience a sudden onset of sleepiness, while people with hypersomnia experience increasing sleepiness over time. Also, people with narcolepsy find daytime sleep refreshing, while people with hypersomnia do not.
People with Kleine-Levin syndrome have symptoms that differ from the symptoms of other forms of hypersomnia. These people may sleep up to 20 or more hours a day in episodes that last for several weeks. In addition, they are often irritable, sometimes to the point of violence. They can be sexually uninhibited (hyper-sexual) and make indiscriminate sexual advances. There may be some confusion and memory deficits, as well. People with Kleine-Levin syndrome often eat uncontrollably and rapidly gain weight, unlike people with other forms of hypersomnia. This form of recurrent hypersomnia is very rare, with only 27 cases described in the scientific literature between 1962 and 2004. The disorder, which most often starts in adolescence, generally lessens and resolves as a person ages.
The causes of hypersomnia remain unclear. There is some speculation that in many cases it can be attributed to problems involving the hypothalamus, but evidence supporting this idea is sparse. In the case of Kleine-Levin, there is some suggestion that onset of the disorder may in some cases be linked to certain viral illnesses.
Demographics
Hypersomnia is an uncommon disorder. In general, no more than 5% of adults complain of excessive sleepiness during the daytime. That does not mean all those who complain of excessive sleepiness have hypersomnia. There are many other possible causes of daytime sleepiness. Of all the people who visit sleep clinics because they feel they are too sleepy during the day, only about 5-10% are diagnosed with primary hypersomnia. Kleine-Levin syndrome is present in about four times more males than females, but it is a very rare syndrome.
Hypersomnia generally appears when the patient is between 15 and 30 years old. It does not begin suddenly but becomes apparent slowly, sometimes over years.
KEY TERMS
Hypothalamus — A part of the forebrain that controls heartbeat, body temperature, thirst, hunger, blood pressure, blood-sugar levels, and other functions.
Narcolepsy — A disorder characterized by frequent and uncontrollable attacks of deep sleep.
Diagnosis
Hypersomnia is characterized by excessive daytime sleepiness, and daytime naps that do not result in a more refreshed or alert feeling. Hypersomnia does not include lack of nighttime sleep. People experiencing problems with nighttime sleep may have insomnia, a separate sleep disorder. In people with insomnia, excessive daytime sleepiness may be a side effect.
The Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR), which presents the guidelines used by the American Psychiatric Association for diagnosis of disorders, states that hypersomnia symptoms must be present for at least a month, and must interfere with a person’s normal activities. Also, the symptoms cannot be attributed to failure to get enough sleep at night or to another sleep disorder. The symptoms cannot be caused by another significant psychological disorder, nor can they be a side effect of a medicinal or illicit drug or a side effect of a general medical condition. For a diagnosis of recurrent hypersomnia, the symptoms must occur for at least three days at a time, and the symptoms have to be present for at least two years.
Treatments
There have been some attempts to use drugs for treating hypersomnia. No substantial body of evidence supports the effectiveness of these treatments. Stimulants are not generally recommended to treat hypersomnia because they treat the symptoms but do not address the cause. Some research suggests that treatments targeting the hypothalamus may be effective therapy for hypersomnia.
Prognosis
Kleine-Levin syndrome has been reported to occasionally resolve by itself around middle age. Except for that syndrome, hypersomnia is considered both a lifelong disorder and one that can be significantly disabling. There is no body of evidence that concludes there is a way to successfully treat the majority of hypersomnia cases.
Resources
BOOKS
Aldrich, Michael S. Sleep Medicines. New York: Oxford University Press, 1999.
American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, 4th ed., Text rev. Washington, D.C.: American Psychiatric Association, 2000.
Chokroverty, Susan, ed. Sleep Disorders Medicine: Basic Science, Technical Considerations, and Clinical Aspects, 2nd ed. Boston: Butterworth-Heinemann, 1999.
Sadock, Benjamin J., and Virginia A. Sadock, eds. Comprehensive Textbook of Psychiatry, 7th ed., Vol. 2. Philadelphia: Lippincott Williams and Wilkins, 2000.
Thorpy, Michael J, ed. Handbook of Sleep Disorders. New York: Marcel Dekker, 1990.
PERIODICALS
Arnulf, I., J.M. Zeitzer, J. File, N. Farber, and E. Mignot. “Kleine-Levin Syndrome: A Systematic Review of 186 Cases in the Literature.” Brain 128 (2006): 2763–76.
Boris, Neil W., Owen R. Hagina, and Gregory P. Steiner. “Case Study: Hypersomnolence and Precocious Puberty in a Child with Pica and Chronic Lead Intoxication.” Journal of the American Academy of Child and Adolescent Psychiatry 35.8 (Aug. 1996): 1050–55.
Mahowald, Mark W., and Carlos H. Schenck. “Insights from Studying Human Sleep Disorders.” Nature 43 (2005): 1279–85.
National Center on Sleep Disorders Research Working Group, Bethesda, Maryland. “Recognizing Problem Sleepiness in Your People.” American Family Physician (Feb. 15, 1999): 937–38.
ORGANIZATIONS
American Academy of Sleep Medicine. 6301 Bandel Road NW, Suite 101, Rochester, MN 55901. Telephone: (507) 287-6006. Web site: <www.asda.org>.
National Organization for Rare Disorders (NORD). P.O. Box 1968/55 Kenosia Ave., Danbury, CT, 06813-1968. Telephone: (203) 744-0100. Web site: <http://www.rarediseases.org>
OTHER
NINDS Hypersomnia Information Page. (2007) Available online at: <http://www.ninds.nih.gov/disorders/hypersomnia/hypersomnia.htm>.
NINDS Kleine-Levin Syndrome Information Page. Available online at: <http://www.ninds.nih.gov/disorders/kleine_levin/kleine_levin.htm>.
Tish Davidson, AM
Emily Jane Willingham, PhD
Kleine-Levin Syndrome
Kleine-Levin Syndrome
Definition
Kleine-Levin syndrome (also known as KLS) is a rare disorder. The most prevalent characteristic of the syndrome is recurring periods of excessive drowsiness and sleep (up to 20 hours per day) that can last weeks.
Description
KLS was first described in 1862 and is considered extremely rare, with only 27 cases reported from 1962 to 2004 in the United States. In addition to excessive drowsiness, an episode of KLS can also involve hypersexuality and compulsive behaviors, including compulsive eating. It usually first manifests in adolescence and appears to lessen and resolve on its own with age. Although cognitive and behavioral disturbances, including transient confusion and memory deficits, can accompany the disorder, there appear to be no lasting, permanent effects. In addition to other manifestations, KLS can be accompanied by mood disorders and an extreme irritability that translates into violent behaviors in atypical cases.
The average number of episodes of KLS among cases is seven, each lasting a median 10 days about every 3.5 months. The median length of time a person experiences the syndrome is eight years, although this time is longer in women and in people who experience less frequent episodes in their first year following onset.
Causes and symptoms
Most studies suggest that KLS is related to the hypothalamus, the organ in the brain that governs appetite, sleep, and hormone cycles, among other things. Researchers have failed to identify specific causes of KLS, although there are some apparent associations between events preceding the first episode of the disorder and its manifestation. The majority of cases are isolated, meaning that they do not appear to have a heritable basis.
Because many people with KLS experienced a viral illness just prior to their first episode, some experts propose that the causative agent is a type of viral or post-autoimmune encephalitis that affects the hypothalamus. Reported infections included tonsillitis, nonspecific flu-like fever, upper respiratory tract infection, and gastroenteritis. One study revealed that three of four autopsied patients with KLS had signs of inflammatory encephalitis in the hypothalamus.
Despite the suggested involvement of the hypothalamus, no association has been found clinically between a KLS episode and changes in hypothalamic hormones, cerebrospinal fluid, or other neurological signs. Similarly, in spite of symptoms such as hypersexuality, there have been no identified related changes in sex steroid hormones. One clinical association with KLS that has been found in 70% of patients is a nonspecific slowing of background brain activity on electroencephalogram testing. All magnetic resonance imaging (MRI) andcatscan (CT) imaging of the brain in KLS cases has been normal.
Symptoms can last weeks or even months. In addition to hypersomnia (excessive sleepiness), symptoms can include excessive eating without regard to content or quantity, extreme irritability, disorientation and confusion, low energy or no energy, hypersensitivity to noise, disconnection from reality, and blurred vision. A person experiencing a KLS episode may also report hallucinations. The abnormally uninhibited sex drive associated with some KLS episodes occurs more frequently in males and manifests in ways that can be alarming: those affected may expose themselves and make unwanted sexual advances. The disorder is episodic, and affected people behave normally between episodes. Intervals between episodes can sometimes last years.
Although an episode can come on without much warning, there are sometimes prodromal (pre-occur-rence) signs that a KLS event is impending, especially a feeling of sudden, overwhelming tiredness. The excessive drowsiness of a KLS episode precludes normal participation in activities. In spite of the hypersomnia, a person experiencing a KLS episode is still able to wake to eat or void.
There may be some depression or amnesia after an attack. Depression can accompany KLS and an episode of KLS can occur with a recurring episode of depression. About half of patients report a depressive mood in conjunction with a KLS event.
KLS can occur as the primary disease, with onset in the teen years, or it can occur secondary to another disease or health problem, such as multiple sclerosis or brain trauma. Although fewer cases of secondary KLS occur compared to primary KLS, patients with secondary
KEY TERMS
Hypersexuality —A clinically significant level of desire to engage in sexual behaviors.
Hypersomnia —Excessive sleepiness.
Hypothalamus —The hypothalamus is part of the brain that links the nervous and endocrine systems and also governs emotion, sexual activity, body temperature, hunger, thirst, and sleep cycles.
KLS may experience much longer and more frequent episodes.
Demographics
There are no published population-based studies reporting KLS incidence. Age at onset is usually in the late teens, and the syndrome is four times more common in males. The average age at onset is about 16.9 years, with a range from 4 to 82 years. About 81%of cases start in the preteen and teen years. Although it occurs more often in males, symptoms may be worse or the disease longer lasting in females.
Diagnosis
According to one source, diagnosing KLS is an difficult process and can result in an average delay of four years before a patient receives the correct diagnosis.
Treatments
No definitive treatment for KLS exists, and response to current treatments can be limited. A clinician can try to address the excessive sleepiness using orally administered stimulants (amphetamines, methylphenidate , modafinil). Because there are crossover characteristics between KLS and other mood disorders, lithium or carbamazepine are sometimes prescribed, and lithium appears to have some beneficial effect on relapse rates in a little less than half of the cases.
Prognosis
Excluding quality-of-life issues, KLS is a benign disorder that usually improves or resolves with age without permanent effects on intellect or physical function.
Prevention
Because the causes of KLS are undefined, prevention measures have not been identified.
Resources
PERIODICALS
Arnulf, I., J.M. Zeitzer, J. File, N. Farber, and E. Mignot, “Kleine-Levin syndrome: a systematic review of 186 cases in the literature.” Brain 128(2006): 2763–2776.
ORGANIZATION
NINDS Kleine-Levin Syndrome Information Page. Available online at <http://www.ninds.nih.gov/disorders/kleine_levin/kleine_levin.htm> (accessed 01/07/07).
Kleine-Levin Syndrome Foundation, P.O. Box 5382, San Jose, CA, 95150-5382. (408) 265-1099. <http://www.klsfoundation.org/site/kls/>.
National Organization for Rare Disorders (NORD), P.O. Box 1968, 55 Kenosia Avenue, Danbury, CT, 06813-1968. (203) 744-0100. <http://www.rarediseases.org>.
National Sleep Foundation, 1522 K Street NW, Suite 500, Washington, D.C. 20005. (202) 347-3471. <http://www.sleepfoundation.org>.
Emily Jane Willingham, Ph.D.
Hypersomnia
Hypersomnia
Definition
Hypersomnia refers to a set of related disorders that involve excessive daytime sleepiness.
Description
There are two main categories of hypersomnia: primary hypersomnia (sometimes called idiopathic hypersomnia) and recurrent hypersomnia (sometimes called recurrent primary hypersomnia). Both are characterized by the same signs and symptoms and differ only in the frequency and regularity with which the symptoms occur.
Primary hypersomnia is characterized by excessive daytime sleepiness over a long period of time. The symptoms are present all, or nearly all, of the time. Recurring hypersomnia involves periods of excessive daytime sleepiness that can last from one to many days, and recur over the course of a year or more. The primary difference between this and primary hypersomnia is that persons experiencing recurring hypersomnia will have prolonged periods where they do not exhibit any signs of hypersomnia, whereas persons experiencing primary hypersomnia are affected by it nearly all the time. One of the best documented forms of recurrent hypersomnia is Kleine-Levin syndrome, although there are other forms as well.
There are many different causes for daytime sleepiness that are not considered hypersomnia, and there are many diseases and disorders in which excessive daytime sleepiness is a primary or secondary symptom. Feelings of daytime sleepiness are often associated with the use of common substances such as caffeine, alcohol, and many medications. Other common factors that can lead to excessive daytime sleepiness that is not considered hypersomnia include shift work and insomnia. Shift work can disrupt the body's natural sleep rhythms. Insomnia can
cause excessive daytime sleepiness because of lack of nighttime sleep, and is a separate disorder.
Demographics
Hypersomnia is an uncommon disorder. In general, 5% or fewer of adults complain of excessive sleepiness during the daytime. That does not mean all those who complain of excessive sleepiness have hypersomnia. There are many other possible causes of daytime sleepiness. Of all the people who visit sleep clinics because they feel they are too sleepy during the day, only about 5–10% are diagnosed with primary hypersomnia. Kleine-Levin syndrome is present in about three times more males than females, but it is a very rare syndrome.
Hypersomnia generally appears when the patient is between 15 and 30 years old. It does not begin suddenly, but becomes apparent slowly, sometimes over years.
Causes and symptoms
People experiencing hypersomnia do not get abnormal amounts of nighttime sleep. However, they often have problems waking up in the morning and staying awake during the day. People with hypersomnia nap frequently, and upon waking from the nap, do not feel refreshed. Hypersomnia is sometimes misdiagnosed as narcolepsy . In many ways the two are similar. One significant difference is that people with narcolepsy experience a sudden onset of sleepiness, while people with hypersomnia experience increasing sleepiness over time. Also, people with narcolepsy find daytime sleep refreshing, while people with hypersomnia do not.
People with Kleine-Levin syndrome have symptoms that differ from the symptoms of other forms of hypersomnia. These people may sleep for 18 or more hours a day. In addition, they are often irritable, uninhibited, and make indiscriminate sexual advances. People with Kleine-Levin syndrome often eat uncontrollably and rapidly gain weight, unlike people with other forms of hypersomnia. This form of recurrent hypersomnia is very rare.
The causes of hypersomnia remain unclear. There is some speculation that in many cases it can be attributed to problems involving the hypothalamus, but there is little evidence to support that claim.
Diagnosis
Hypersomnia is characterized by excessive daytime sleepiness, and daytime naps that do not result in a more refreshed or alert feeling. Hypersomnia does not include lack of nighttime sleep. People experiencing problems with nighttime sleep may have insomnia, a separate sleep disorder. In people with insomnia, excessive daytime sleepiness may be a side effect.
The Diagnostic and Statistical Manual of Mental Disorders which presents the guidelines used by the American Psychiatric Association for diagnosis of disorders, states that symptoms must be present for at least a month, and must interfere with a person's normal activities. Also, the symptoms cannot be attributed to failure to get enough sleep at night or to another sleep disorder. The symptoms cannot be caused by another significant psychological disorder, nor can they be a side effect of a medicinal or illicit drug or a side effect of a general medical condition. For a diagnosis of recurrent hypersomnia, the symptoms must occur for at least three days at a time, and the symptoms have to be present for at least two years.
Treatment team
A number of specialists deal with sleep problems, including internal medicine physicians, psychiatrists, neurologists, and sleep disorder specialists.
Treatments
There have been some attempts at using drugs to treat hypersomnia. No substantial body of evidence supports the effectiveness of these treatments. Stimulants are not generally recommended to treat hypersomnia as they treat the symptoms but not the base problem. Some researchers believe that treatment of the hypothalamus may be a possible treatment for hypersomnia.
Prognosis
Kleine-Levin syndrome has been reported to occasionally resolve by itself around middle age. Except for that syndrome, hypersomnia is considered both a lifelong disorder and one that can be significantly disabling. There is no body of evidence that concludes there is a way to treat the majority of hypersomnia cases successfully.
Resources
BOOKS
Aldrich, Michael S. Sleep Medicines. New York: Oxford University Press, 1999.
American Psychiatric Association Diagnostic and Statistical Manual of Mental Disorders. 4th edition, text revised. Washington DC: American Psychiatric Association, 2000.
Chokroverty, Susan, ed. Sleep Disorders Medicine: Basic Science, Technical Considerations, and Clinical Aspects. 2nd ed. Boston: Butterworth-Heinemann, 1999.
Sadock, Benjamin J. and Virginia A. Sadock, eds. Comprehensive Textbook of Psychiatry. 7th edition, vol. 2. Philadelphia: Lippincott Williams and Wilkins, 2000.
Thorpy, Michael J, ed. Handbook of Sleep Disorders. New York: Marcel Dekker Inc, 1990.
PERIODICALS
Boris, Neil W., Owen R. Hagina, Gregory P. Steiner. "Case Study: hypersomnolence and precocious puberty in a child with pica and chronic lead intoxication." Journal of the American Academy of Child and Adolescent Psychiatry 35, no. 8 (August 1996): 1050-1055.
National Center on Sleep Disorders Research Working Group, Bethesda, Maryland. "Recognizing Problem Sleepiness in Your People." American Family Physician (February 15, 1999): 937-38.
ORGANIZATIONS
American Academy of Sleep Medicine. 6301 Bandel Road NW, Suite 101, Rochester, MN 55901. (507) 287-6006. <www.asda.org>.
Tish Davidson, AM
Rosalyn Carson-Dewitt, MD
Hypersomnia
Hypersomnia
Definition
Hypersomnia refers to a set of related disorders that involve excessive daytime sleepiness.
Description
There are two main categories of hypersomnia: primary hypersomnia (sometimes called idiopathic hypersomnia) and recurrent hypersomnia (sometimes called recurrent primary hypersomnia). Both are characterized by the same signs and symptoms and differ only in the frequency and regularity with which the symptoms occur.
Primary hypersomnia is characterized by excessive daytime sleepiness over a long period of time. The symptoms are present all, or nearly all, of the time. Recurring hypersomnia involves periods of excessive daytime sleepiness that can last from one to many days, and recur over the course of a year or more. The primary difference between this and primary hypersomnia is that persons experiencing recurring hypersomnia will have prolonged periods where they do not exhibit any signs of hypersomnia, whereas persons experiencing primary hypersomnia are affected by it nearly all the time. One of the best documented forms of recurrent hypersomnia is Kleine-Levin syndrome, although there are other forms as well.
There are many different causes for daytime sleepiness that are not considered hypersomnia, and there are many diseases and disorders in which excessive daytime sleepiness is a primary or secondary symptom. Feelings of daytime sleepiness are often associated with the use of common substances such as caffeine, alcohol, and many medications. Other common factors that can lead to excessive daytime sleepiness that is not considered hypersomnia include shift work and insomnia . Shift work can disrupt the body's natural sleep rhythms. Insomnia can cause excessive daytime sleepiness because of lack of nighttime sleep, and is a separate disorder.
Causes and symptoms
People experiencing hypersomnia do not get abnormal amounts of nighttime sleep. However, they often have problems waking up in the morning and staying awake during the day. People with hypersomnia nap frequently, and upon waking from the nap, do not feel refreshed. Hypersomnia is sometimes misdiagnosed as narcolepsy . In many ways the two are similar. One significant difference is that people with narcolepsy experience a sudden onset of sleepiness, while people with hypersomnia experience increasing sleepiness over time. Also, people with narcolepsy find daytime sleep refreshing, while people with hypersomnia do not.
People with Kleine-Levin syndrome have symptoms that differ from the symptoms of other forms of hypersomnia. These people may sleep for 18 or more hours a day. In addition, they are often irritable, uninhibited, and make indiscriminate sexual advances. People with Kleine-Levin syndrome often eat uncontrollably and rapidly gain weight, unlike people with other forms of hypersomnia. This form of recurrent hypersomnia is very rare.
The causes of hypersomnia remain unclear. There is some speculation that in many cases it can be attributed to problems involving the hypothalamus, but there is little evidence to support that claim.
Demographics
Hypersomnia is an uncommon disorder. In general, 5% or fewer of adults complain of excessive sleepiness during the daytime. That does not mean all those who complain of excessive sleepiness have hypersomnia. There are many other possible causes of daytime sleepiness. Of all the people who visit sleep clinics because they feel they are too sleepy during the day, only about 5–10% are diagnosed with primary hypersomnia. Kleine-Levin syndrome is present in about three times more males than females, but it is a very rare syndrome.
Hypersomnia generally appears when the patient is between 15 and 30 years old. It does not begin suddenly, but becomes apparent slowly, sometimes over years.
Diagnosis
Hypersomnia is characterized by excessive daytime sleepiness, and daytime naps that do not result in a more refreshed or alert feeling. Hypersomnia does not include lack of nighttime sleep. People experiencing problems with nighttime sleep may have insomnia, a separate sleep disorder. In people with insomnia, excessive daytime sleepiness may be a side effect.
The Diagnostic and Statistical Manual of Mental Disorders , which presents the guidelines used by the American Psychiatric Association for diagnosis of disorders, states that symptoms must be present for at least a month, and must interfere with a person's normal activities. Also, the symptoms cannot be attributed to failure to get enough sleep at night or to another sleep disorder. The symptoms cannot be caused by another significant psychological disorder, nor can they be a side effect of a medicinal or illicit drug or a side effect of a general medical condition. For a diagnosis of recurrent hypersomnia, the symptoms must occur for at least three days at a time, and the symptoms have to be present for at least two years.
Treatments
There have been some attempts at using drugs to treat hypersomnia. No substantial body of evidence supports the effectiveness of these treatments. Stimulants are not generally recommended to treat hypersomnia as they treat the symptoms but not the base problem. Some researchers believe that treatment of the hypothalamus may be a possible treatment for hypersomnia.
Prognosis
Kleine-Levin syndrome has been reported to resolve occasionally by itself around middle age. Except for that syndrome, hypersomnia is considered both a lifelong disorder and one that can be significantly disabling. There is no body of evidence that concludes there is a way to treat the majority of hypersomnia cases successfully.
Resources
BOOKS
Aldrich, Michael S. Sleep Medicines. New York: Oxford University Press, 1999.
American Psychiatric Association Diagnostic and Statistical Manual of Mental Disorders. 4th edition, text revised. Washington DC: American Psychiatric Association, 2000.
Chokroverty, Susan, ed. Sleep Disorders Medicine: Basic Science, Technical Considerations, and Clinical Aspects. 2nd ed. Boston: Butterworth-Heinemann, 1999.
Sadock, Benjamin J. and Virginia A. Sadock, eds. Comprehensive Textbook of Psychiatry. 7th edition, vol. 2. Philadelphia: Lippincott Williams and Wilkins, 2000.
Thorpy, Michael J, ed. Handbook of Sleep Disorders. New York: Marcel Dekker Inc, 1990.
PERIODICALS
Boris, Neil W., Owen R. Hagina, Gregory P. Steiner. "Case Study: hypersomnolence and precocious puberty in a child with pica and chronic lead intoxication." Journal of the American Academy of Child and Adolescent Psychiatry 35, no. 8 (August 1996): 1050-1055.
National Center on Sleep Disorders Research Working Group, Bethesda, Maryland. "Recognizing Problem Sleepiness in Your People." American Family Physician (February 15, 1999): 937-38.
ORGANIZATIONS
American Academy of Sleep Medicine. 6301 Bandel Road NW, Suite 101, Rochester, MN 55901. (507) 287-6006. <www.asda.org>.
Tish Davidson, A.M.