Hypersomnia is a neurological disorder of excessive time spent sleeping or excessive sleepiness. It can have many possible causes (such as

seasonal affective disorder Seasonal affective disorder (SAD) is a mood disorder subset, in which people who have normal mental health throughout most of the year exhibit depressive symptoms at the same time each year. Common symptoms include sleeping too much, having li ...

) and can cause distress and problems with functioning. In the fifth edition of the '' Diagnostic and Statistical Manual of Mental Disorders'' (

DSM-5 The ''Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition'' (DSM-5), is the 2013 update to the '' Diagnostic and Statistical Manual of Mental Disorders'', the taxonomic and diagnostic tool published by the American Psychiatri ...

), hypersomnolence, of which there are several subtypes, appears under

sleep-wake disorder A sleep disorder, or somnipathy, is a medical disorder of an individual's sleep patterns. Some sleep disorders are severe enough to interfere with normal physical, mental, social and emotional functioning. Polysomnography and actigraphy are test ...

s. Hypersomnia is a pathological state characterized by a lack of

alertness Alertness is the state of active attention by high sensory awareness such as being watchful and prompt to meet danger or emergency, or being quick to perceive and act. It is related for psychology . A lack of alertness is a symptom of a ...

during the waking episodes of the day.American Academy of Sleep Medicine. The international classification of sleep disorders: diagnostic & coding manual (2nd ed). Westchester, IL: American Academy of Sleep Medicine, 2005. It is not to be confused with fatigue, which is a normal physiological state. Daytime sleepiness appears most commonly during situations where little interaction is needed. Since the patients’ attention levels (

wakefulness Wakefulness is a daily recurring brain state and state of consciousness in which an individual is conscious and engages in coherent cognitive and behavioral responses to the external world. Being awake is the opposite of being asleep, in which m ...

) are impaired, their quality of life may be impacted as well.Morgenthaler, T. I., Kapur, V. K., Brown, T. M., Swick, T. J., Alessi, C., Aurora, R. N., … Zak, R. (2007). Practice Parameters for the Treatment of Narcolepsy and other Hypersomnias of Central Origin. ''Sleep, 30''(12), 1705‑1711. https://doi.org/10.1093/sleep/30.12.1705 This is especially true for people whose jobs request high levels of attention, such as in the healthcare field.

Symptoms

The main symptom of hypersomnia is excessive daytime sleepiness (EDS), or prolonged nighttime sleep, which has occurred for at least 3 months prior to diagnosis. Sleep drunkenness is also a symptom found in hypersomniac patients.Roth, B. (1972). Hypersomnia With « Sleep Drunkenness ». ''Archives of General Psychiatry, 26''(5), 456. https://doi.org/10.1001/archpsyc.1972.01750230066013Trotti, L. M. (2017). Waking up is the hardest thing I do all day: Sleep inertia and sleep drunkenness. ''Sleep medicine reviews, 35'', 76–84. It is a difficulty transitioning from sleep to wake. Individuals experiencing sleep drunkenness report waking with confusion, disorientation, slowness and repeated returns to sleep. It also appears in non-hypersomniac persons, for example after a night of insufficient sleep. Fatigue and consumption of alcohol or hypnotics can cause sleep drunkenness as well. It is also associated with irritability: people who get angry shortly before sleeping tend to experience sleep drunkenness. According to the American Academy of Sleep Medicine, hypersomniac patients often take long naps during the day that are mostly unrefreshing. Researchers found that naps are usually more frequent and longer in patients than in controls.Vernet, C., Leu-Semenescu, S., Buzare, M.-A., & Arnulf, I. (2010). Subjective symptoms in idiopathic hypersomnia: Beyond excessive sleepiness. ''Journal of sleep research, 19''(4), 525–534. Furthermore, 75% of the patients report that short naps are not refreshing, compared to controls.

Diagnosis

"The severity of daytime sleepiness needs to be quantified by subjective scales (at least the Epworth Sleepiness Scale) and objective tests such as the multiple sleep latency test (MSLT)." The Stanford sleepiness scale (SSS) is another frequently-used subjective measurement of sleepiness. After it is determined that excessive daytime sleepiness is present, a complete medical examination and full evaluation of potential disorders in the differential diagnosis (which can be tedious, expensive and time-consuming) should be undertaken.

Differential diagnosis

Hypersomnia can be primary (of central/brain origin), or it can be secondary to any of numerous medical conditions. More than one type of hypersomnia can coexist in a single patient. Even in the presence of a known cause of hypersomnia, the contribution of this cause to the complaint of excessive daytime sleepiness needs to be assessed. When specific treatments of the known condition do not fully suppress excessive daytime sleepiness, additional causes of hypersomnia should be sought. For example, if a patient with sleep apnea is treated with CPAP (

continuous positive airway pressure Continuous positive airway pressure (CPAP) is a form of positive airway pressure (PAP) ventilation in which a constant level of pressure greater than atmospheric pressure is continuously applied to the upper respiratory tract of a person. The ...

), which resolves their apneas but not their excessive daytime sleepiness, it is necessary to seek other causes for the excessive daytime sleepiness. Obstructive sleep apnea "occurs frequently in

narcolepsy Narcolepsy is a long-term neurological disorder that involves a decreased ability to regulate sleep–wake cycles. Symptoms often include periods of excessive daytime sleepiness and brief involuntary sleep episodes. About 70% of those affect ...

and may delay the diagnosis of narcolepsy by several years and interfere with its proper management."

Primary hypersomnias

The true primary hypersomnias include: *

Narcolepsy Narcolepsy is a long-term neurological disorder that involves a decreased ability to regulate sleep–wake cycles. Symptoms often include periods of excessive daytime sleepiness and brief involuntary sleep episodes. About 70% of those affect ...

(with and without

cataplexy Cataplexy is a sudden and transient episode of muscle weakness accompanied by full conscious awareness, typically triggered by emotions such as laughing, crying, or terror. Cataplexy affects approximately 70% of people who have narcolepsy, and is ...

) *

Idiopathic hypersomnia Idiopathic hypersomnia (IH) is a neurological disorder which is characterized primarily by excessive sleep and excessive daytime sleepiness (EDS). The condition typically becomes evident in early adulthood and most patients diagnosed with IH will ...

* Recurrent hypersomnias (like Kleine-Levin syndrome)

Primary hypersomnia mimics

There are also several genetic disorders that may be associated with primary/central hypersomnia. These include the following: Prader-Willi syndrome; Norrie disease; Niemann–Pick disease, type C; and

myotonic dystrophy Myotonic dystrophy (DM) is a type of muscular dystrophy, a group of genetic disorders that cause progressive muscle loss and weakness. In DM, muscles are often unable to relax after contraction. Other manifestations may include cataracts, intel ...

. However, hypersomnia in these syndromes may also be associated with other secondary causes, so it is important to complete a full evaluation. Myotonic dystrophy is often associated with SOREMPs ( sleep onset REM periods, such as occur in narcolepsy). There are many

neurological disorders A neurological disorder is any disorder of the nervous system. Structural, biochemical or electrical abnormalities in the brain, spinal cord or other nerves can result in a range of symptoms. Examples of symptoms include paralysis, muscle weaknes ...

that may mimic the primary hypersomnias, narcolepsy and idiopathic hypersomnia: brain tumors; stroke-provoking lesions; and dysfunction in the

thalamus The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all directions, ...

hypothalamus The hypothalamus () is a part of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamu ...

, or brainstem. Also, neurodegenerative conditions such as Alzheimer's disease,

Parkinson's disease Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disease worsens, non-motor symptoms becom ...

, or multiple system atrophy are frequently associated with primary hypersomnia. However, in these cases, one must still rule out other secondary causes. Early

hydrocephalus Hydrocephalus is a condition in which an accumulation of cerebrospinal fluid (CSF) occurs within the brain. This typically causes increased pressure inside the skull. Older people may have headaches, double vision, poor balance, urinary inc ...

can also cause severe excessive daytime sleepiness. Additionally,

head trauma A head injury is any injury that results in trauma to the skull or brain. The terms ''traumatic brain injury'' and ''head injury'' are often used interchangeably in the medical literature. Because head injuries cover such a broad scope of inju ...

can be associated with a primary/central hypersomnia, and symptoms similar to those of idiopathic hypersomnia can be seen within 6–18 months following the trauma. However, the associated symptoms of headaches, memory loss, and lack of concentration may be more frequent in head trauma than in idiopathic hypersomnia. "The possibility of secondary narcolepsy following head injury in previously asymptomatic individuals has also been reported."

Secondary hypersomnias

Secondary hypersomnias are extremely numerous. Hypersomnia can be secondary to disorders such as

clinical depression Major depressive disorder (MDD), also known as clinical depression, is a mental disorder characterized by at least two weeks of pervasive low mood, low self-esteem, and loss of interest or pleasure in normally enjoyable activities. Intro ...

, multiple sclerosis, encephalitis,

epilepsy Epilepsy is a group of non-communicable neurological disorders characterized by recurrent epileptic seizures. Epileptic seizures can vary from brief and nearly undetectable periods to long periods of vigorous shaking due to abnormal electrica ...

, or

obesity Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's ...

. Hypersomnia can also be a symptom of other sleep disorders, like

sleep apnea Sleep apnea, also spelled sleep apnoea, is a sleep disorder in which pauses in breathing or periods of shallow breathing during sleep occur more often than normal. Each pause can last for a few seconds to a few minutes and they happen many tim ...

. It may occur as an

adverse effect An adverse effect is an undesired harmful effect resulting from a medication or other intervention, such as surgery. An adverse effect may be termed a " side effect", when judged to be secondary to a main or therapeutic effect. The term compl ...

of taking certain medications, of withdrawal from some medications, or of substance use. A genetic predisposition may also be a factor. In some cases it results from a physical problem, such as a tumor, head trauma, or dysfunction of the autonomic or

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all p ...

. Sleep apnea is the second most frequent cause of secondary hypersomnia, affecting up to 4% of middle-aged adults, mostly men. Upper airway resistance syndrome (UARS) is a clinical variant of sleep apnea that can also cause hypersomnia. Just as other sleep disorders (like narcolepsy) can coexist with sleep apnea, the same is true for UARS. There are many cases of UARS in which excessive daytime sleepiness persists after CPAP treatment, indicating an additional cause, or causes, of the hypersomnia and requiring further evaluation. Sleep movement disorders, such as

restless legs syndrome Restless legs syndrome (RLS), also known as Willis-Ekbom disease (WED), is generally a long-term disorder that causes a strong urge to move one's legs. There is often an unpleasant feeling in the legs that improves somewhat by moving them. This ...

(RLS) and

periodic limb movement disorder Periodic limb movement disorder (PLMD) is a sleep disorder where the patient moves limbs involuntarily and periodically during sleep, and has symptoms or problems related to the movement. PLMD should not be confused with restless legs syndrome (RL ...

(PLMD or PLMS) can also cause secondary hypersomnia. Although RLS does commonly cause excessive daytime sleepiness, PLMS does not. There is no evidence that PLMS plays "a role in the etiology of daytime sleepiness. In fact, two studies showed no correlation between PLMS and objective measures of excessive daytime sleepiness. In addition, EDS in these patients is best treated with psychostimulants—and not with dopaminergic agents known to suppress PLMS."

Neuromuscular disease A neuromuscular disease is any disease affecting the peripheral nervous system (PNS), the neuromuscular junction, or skeletal muscle, all of which are components of the motor unit. Damage to any of these structures can cause muscle atrophy and wea ...

s and spinal cord diseases often lead to sleep disturbances due to respiratory dysfunction causing sleep apnea, and they may also cause

insomnia Insomnia, also known as sleeplessness, is a sleep disorder in which people have trouble sleeping. They may have difficulty falling asleep, or staying asleep as long as desired. Insomnia is typically followed by daytime sleepiness, low energy, ...

related to pain. "Other sleep alterations, such as periodic limb movement disorders in patients with spinal cord disease, have also been uncovered with the widespread use of

polysomnography Polysomnography (PSG), a type of sleep study, is a multi-parameter study of sleep and a diagnostic tool in sleep medicine. The test result is called a polysomnogram, also abbreviated PSG. The name is derived from Greek and Latin roots: the Gre ...

." Primary hypersomnia in

diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ...

hepatic encephalopathy Hepatic encephalopathy (HE) is an altered level of consciousness as a result of liver failure. Its onset may be gradual or sudden. Other symptoms may include movement problems, changes in mood, or changes in personality. In the advanced stage ...

, and acromegaly is rarely reported, but these medical conditions may also be associated with hypersomnia secondary to

and

(PLMD). Chronic fatigue syndrome and fibromyalgia can also be associated with hypersomnia. Chronic fatigue syndrome is "characterized by persistent or relapsing fatigue that does not resolve with sleep or rest. Polysomnography shows reduced sleep efficiency and may include alpha intrusion into sleep

EEG Electroencephalography (EEG) is a method to record an electrogram of the spontaneous electrical activity of the brain. The biosignals detected by EEG have been shown to represent the postsynaptic potentials of pyramidal neurons in the neocortex ...

. It is likely that a number of cases labeled as chronic fatigue syndrome are unrecognized cases of upper airway resistance syndrome" or other sleep disorders, such as narcolepsy, sleep apnea, PLMD, etc. As with chronic fatigue syndrome, fibromyalgia may be associated with anomalous alpha wave activity (typically associated with arousal states) during NREM sleep. Also, researchers have shown that disrupting stage IV sleep consistently in young, healthy subjects causes a significant increase in muscle tenderness—similar to that experienced in "neurasthenic musculoskeletal pain syndrome". This pain resolved when the subjects were able to resume their normal sleep patterns. Chronic kidney disease is commonly associated with sleep symptoms and excessive daytime sleepiness. 80% of those on dialysis have sleep disturbances. Sleep apnea can occur 10 times as often in uremic patients than in the general population and can affect up to 30-80% of patients on dialysis, though nighttime dialysis can improve this. About 50% of dialysis patients have hypersomnia, as severe kidney disease can cause uremic encephalopathy, increased sleep-inducing cytokines, and impaired sleep efficiency. About 70% of dialysis patients are affected by insomnia, and RLS and PLMD affect 30%, though these may improve after dialysis or kidney transplant. Most forms of cancer and their therapies can cause fatigue and disturbed sleep, affecting 25-99% of patients and often lasting for years after treatment completion. "Insomnia is common and a predictor of fatigue in cancer patients, and polysomnography demonstrates reduced sleep efficiency, prolonged initial sleep latency, and increased wake time during the night."

Paraneoplastic syndromes A paraneoplastic syndrome is a syndrome (a set of signs and symptoms) that is the consequence of a tumor in the body (usually a cancerous one), specifically due to the production of chemical signaling molecules (such as hormones or cytokines) by ...

can also cause insomnia, hypersomnia, and

parasomnia Parasomnias are a category of sleep disorders that involve abnormal movements, behaviors, emotions, perceptions, and dreams that occur while falling asleep, sleeping, between sleep stages, or during arousal from sleep. Parasomnias are dissociat ...

s. Autoimmune diseases, especially lupus and

rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and hands are invol ...

, are often associated with hypersomnia.

Morvan's syndrome Morvan's syndrome is a rare, life-threatening autoimmune disease named after the nineteenth century French physician Augustin Marie Morvan. "La chorée fibrillaire" was first coined by Morvan in 1890 when describing patients with multiple, irregu ...

is an example of a rarer autoimmune illness that can also lead to hypersomnia.

Celiac disease Coeliac disease (British English) or celiac disease (American English) is a long-term autoimmune disorder, primarily affecting the small intestine, where individuals develop intolerance to gluten, present in foods such as wheat, rye and barle ...

is another autoimmune disease associated with poor sleep quality (which may lead to hypersomnia), "not only at diagnosis but also during treatment with a gluten-free diet." There are also some case reports of central hypersomnia in celiac disease. And RLS "has been shown to be frequent in celiac disease," presumably due to its associated iron deficiency. Hypothyroidism and

iron deficiency Iron deficiency, or sideropenia, is the state in which a body lacks enough iron to supply its needs. Iron is present in all cells in the human body and has several vital functions, such as carrying oxygen to the tissues from the lungs as a key ...

with or without (iron-deficiency

anemia Anemia or anaemia (British English) is a blood disorder in which the blood has a reduced ability to carry oxygen due to a lower than normal number of red blood cells, or a reduction in the amount of hemoglobin. When anemia comes on slowly, t ...

) can also cause secondary hypersomnia. Various tests for these disorders are done so they can be treated. Hypersomnia can also develop within months after viral infections such as

Whipple's disease Whipple's disease is a rare systemic infectious disease caused by the bacterium '' Tropheryma whipplei''. First described by George Hoyt Whipple in 1907 and commonly considered as a gastrointestinal disorder, Whipple's disease primarily causes ma ...

mononucleosis Infectious mononucleosis (IM, mono), also known as glandular fever, is an infection usually caused by the Epstein–Barr virus (EBV). Most people are infected by the virus as children, when the disease produces few or no symptoms. In young adult ...

HIV The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune ...

, and

Guillain–Barré syndrome Guillain–Barré syndrome (GBS) is a rapid-onset muscle weakness caused by the immune system damaging the peripheral nervous system. Typically, both sides of the body are involved, and the initial symptoms are changes in sensation or pain oft ...

. Behaviorally induced insufficient sleep syndrome must be considered in the differential diagnosis of secondary hypersomnia. This disorder occurs in individuals who fail to get sufficient sleep for at least three months. In this case, the patient has chronic sleep deprivation, although they may not necessarily be aware of it. This situation is becoming more prevalent in western society due to the modern demands and expectations placed upon the individual. Many

medication A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy ( pharmacotherapy) is an important part of the medical field and ...

s can lead to secondary hypersomnia. Therefore, a patient's complete medication list should be carefully reviewed for sleepiness or fatigue as side effects. In these cases, careful withdrawal from the possibly offending medication(s) is needed; then, medication substitution can be undertaken.

Mood disorders A mood disorder, also known as an affective disorder, is any of a group of conditions of mental and behavioral disorder where a disturbance in the person's mood is the main underlying feature. The classification is in the '' Diagnostic and St ...

, like depression, anxiety disorder and

bipolar disorder Bipolar disorder, previously known as manic depression, is a mental disorder characterized by periods of depression and periods of abnormally elevated mood that last from days to weeks each. If the elevated mood is severe or associated with ...

, can also be associated with hypersomnia. The complaint of excessive daytime sleepiness in these conditions is often associated with poor sleep at night. "In that sense, insomnia and EDS are frequently associated, especially in cases of depression." Hypersomnia in mood disorders seems to be primarily related to "lack of interest and decreased energy inherent in the depressed condition rather than an increase in sleep or REM sleep propensity". In all cases with these mood disorders, the MSLT is normal (not too short and no SOREMPs).

Posttraumatic hypersomnias

In some cases, hypersomnia can be caused by a brain injury. Researchers found that the level of sleepiness is correlated with the severity of the injury.Watson, N. F., Dikmen, S., Machamer, J., Doherty, M., & Temkin, N. (2007). Hypersomnia following traumatic brain injury. ''Journal of Clinical Sleep Medicine, 3''(04), 363–368. Even if patients reported an improvement, sleepiness remained present for a year in about a quarter of patients with traumatic brain injury.

Recurrent hypersomnias

Recurrent hypersomnias are defined by several episodes of hypersomnia persisting from a few days to weeks.Dauvilliers, Y., & Buguet, A. (2005). Hypersomnia. ''Dialogues in clinical neuroscience, 7''(4), 347. These episodes can occur weeks or months apart from each other. There are 2 subtypes of recurrent hypersomnias: Kleine-Levin syndrome and menstrual-related hypersomnia.Billiard, M., & Podesta, C. (2013). Recurrent hypersomnia following traumatic brain injury. ''Sleep Medicine, 14''(5), 462‑465. https://doi.org/10.1016/j.sleep.2013.01.009 Kleine-Levin syndrome is characterized by the association of episodes of hypersomnias with behavioral, cognitive and mood abnormalities. The behavioral disturbances can be composed of

hyperphagia Polyphagia or hyperphagia is an abnormally strong, incessant sensation of hunger or desire to eat often leading to overeating. In contrast to an increase in appetite following exercise, polyphagia does not subside after eating and often leads to ...

irritability Irritability (also called as crankiness) is the excitatory ability that living organisms have to respond to changes in their environment. The term is used for both the physiological reaction to stimuli and for the pathological, abnormal or excessi ...

, or sexual disinhibition. The cognitive disorders consist of confusion, hallucinations or delusions. Mood symptoms are characterized by anxiety or depression. Menstrual-related hypersomnia is characterized by episodes of excessive sleepiness associated with the menstrual cycle. Researchers found that the degree of premenstrual symptoms were correlated with daytime sleepiness. Unlike Kleine-Levin syndrome,

and

hypersexuality Hypersexuality is extremely frequent or suddenly increased libido. It is controversial whether it should be included as a clinical diagnosis used by mental healthcare professionals. Nymphomania and satyriasis were terms previously used for the c ...

are not reported in people with menstrual-related hypersomnia, but hypophagia could be present.Harris, S. F., Monderer, R. S., & Thorpy, M. (2012). Hypersomnias of Central Origin. Neurologic Clinics, 30(4), 1027‑1044. https://doi.org/10.1016/j.ncl.2012.08.002 Ordinarily, these episodes appear 2 weeks before menstruation. A few studies have attested that some hormones as

prolactin Prolactin (PRL), also known as lactotropin, is a protein best known for its role in enabling mammals to produce milk. It is influential in over 300 separate processes in various vertebrates, including humans. Prolactin is secreted from the pit ...

and progesterone could be responsible for Menstrual-Related Hypersomnia. Therefore, different contraceptive pills could improve the symptoms. The sleep architecture changes. There is a decrease of slow-wave sleep and an increase of slow-Theta-wave activity.

Assessment tools

Polysomnography

Polysomnography is an objective sleep assessment method. It comprises a lot of electrodes which measure physiological variables related to sleep.Marino, M., Li, Y., Rueschman, M. N., Winkelman, J. W., Ellenbogen, J. M., Solet, J. M., … Buxton, O. M. (2013). Measuring sleep: Accuracy, sensitivity, and specificity of wrist actigraphy compared to polysomnography. ''Sleep, 36''(11), 1747–1755. Polysomnography often includes electroencephalography, electromyography, electrocardiography, muscle activity and respiratory function. Polysomnography is helpful to identify the very short sleep onset latency period, the very efficient sleep (more than 90%), the increased slow wave sleep, and sometimes an elevated amount of sleep spindles in idiopathic hypersomnia patients.

Multiple sleep latency test (MSLT)

The 'multiple sleep latency test' (MSLT) is an objective tool which indicates the degree of sleepiness by measuring the sleep latency (i.e. the speed of falling asleep).Carskadon, M. A. (1986). Guidelines for the multiple sleep latency test (MSLT): A standard measure of sleepiness. ''Sleep, 9''(4), 519–524.Littner, M. R., Kushida, C., Wise, M., G. Davila, D., Morgenthaler, T., Lee-Chiong, T., … Berry, R. B. (2005). Practice parameters for clinical use of the multiple sleep latency test and the maintenance of wakefulness test. ''Sleep, 28''(1), 113–121. It also gives information regarding the presence of abnormal REM sleep onset episodes. During that test, patients have a series of opportunities to sleep at 2-h intervals across the day in a darkened room and with no external alerting influences. The MSLT is often administered the day after recording the polysomnography, and the mean sleep latency score is often found to be around (or less than) 8 minutes in idiopathic hypersomnia patients. Some patients might even have a sleep onset latency of 5 minutes or less. These patients are often even more aware of sleeping during naps than narcolepsy patients.

Actigraphy

Actigraphy, which operates by analyzing the patient's limb movements, is used to record the sleep and wake cycles.Ancoli-Israel, S., Cole, R., Alessi, C., Chambers, M., Moorcroft, W., & Pollak, C. P. (2003). The role of actigraphy in the study of sleep and circadian rhythms. ''Sleep, 26''(3), 342–392. In order to report them, the patient has to wear continuously a device on his or her wrist, which looks like a watch and does not contain any electrodes.Lichstein, K. L., Stone, K. C., Donaldson, J., Nau, S. D., Soeffing, J. P., Murray, D., … Aguillard, R. N. (2006). Actigraphy validation with insomnia. ''Sleep, 29''(2), 232–239. The advantage actigraphy shows over polysomnography is that it is possible to record for 24-hours a day for weeks. Furthermore, unlike the polysomnography, it is less expensive and non-invasive. An actigraphy over several days can show longer sleep periods, which are characteristic for idiopathic hypersomnia. Actigraphy is also helpful in ruling out other sleep disorders, especially circadian disorders, leading to an excess of sleepiness during the day, too.

The maintenance of wakefulness test (MWT)

The 'maintenance of wakefulness test' (MWT) is a test that measures the ability to stay awake. It is used to diagnose disorders of excessive somnolence, such as hypersomnia, narcolepsy or obstructive sleep apnea. During that test, patients sit comfortably and are instructed to try to stay awake.

The Stanford sleepiness scale (SSS)

The Stanford sleepiness scale (SSS) is a self-report scale that measures the different steps of sleepiness.Hoddes, E., Zarcone, V., Smythe, H., Phillips, R., & Dement, W. C. (1973). Quantification of Sleepiness: A New Approach. ''Psychophysiology, 10''(4), 431‑436. https://doi.org/10.1111/j.1469-8986.1973.tb00801.x For each statement, patients report their level of sleepiness using a 7-point scale, going from very alert to excessively sleepy. Researchers found that the SSS was highly correlated with performances to monotonous and boring tasks, which are found to be very sensitive to sleepiness. These results suggest that the SSS is a good tool to assess sleepiness in patients.

The Epworth sleepiness scale (ESS)

The 'Epworth sleepiness scale' (ESS) is also a self-reported questionnaire that measures the general level of sleepiness in a day Johns, Murray W. (1991). A new method for measuring daytime sleepiness: The Epworth sleepiness scale. ''Sleep, 14''(6), 540–545. The patients have to rate specific daily situations by means of a scale going from 0 (would never doze) to 3 (high chance of dozing). The results found in the ESS correlate with the sleep latency indicated by the Multiple Sleep Latency Test.

Treatment

Although there has been no cure of chronic hypersomnia, there are several treatments that may improve patients' quality of life—depending on the specific cause or causes of hypersomnia that are diagnosed. Because the causes of hypersomnia are unknown, it is only possible to treat symptoms and not directly the cause of this disorder. Behavioral treatments, as well as sleep hygiene, have to be discussed with the patient and are recommended. There are several pharmacological agents that have been prescribed to patients with hypersomnia, but few have been found to be efficient. Modafinil has been found to be the most effective drug against the excessive sleepiness, and has even been shown to be helpful in children with hypersomnia. The dosage is started at 100 mg per day, and then slowly increased to 400 mg per day. In general, patients with hypersomnia or excessive sleepiness should only go to bed to sleep or for sexual activity.McWhirter, D., Bae, C., & Budur, K. (2007). The Assessment, Diagnosis, and Treatment of Excessive Sleepiness. ''Psychiatry (Edgmont), 4''(9), 26‑35. All other activities, such as eating or watching television, should be done elsewhere. For those patients, it is also important to go to bed only when they feel tired, than trying to fall asleep for hours. In that case, they probably should get out of bed and read or watch television until they get sleepy.

Epidemiology

Hypersomnia affects approximately 5% to 10% of the general population, "with a higher prevalence for men due to the

syndromes".

References

External links

Help: I can't stay awake!
- Public Radio Interview with Dr. David Rye * - "Primary Hypersomnia" {{Bipolar disorder Sleep disorders