|Specialty||Sleep medicine, Neurology, Psychiatry|
Idiopathic hypersomnia (IH) is a neurological disorder which is characterized primarily by excessive sleep and excessive daytime sleepiness (EDS). Historically, it has been rarely diagnosed, and is often very difficult to diagnose at an early stage. It is often a debilitating, lifelong, and chronic disease. There is a very low level of public awareness of idiopathic hypersomnia, which can lead to stigma for those who suffer from it. As of June 2021[update], several off-label treatments exist (primarily FDA-approved narcolepsy medications).
Idiopathic hypersomnia may also be referred to as IH, IHS, primary hypersomnia, central hypersomnia, or hypersomnia of brain origin. The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) defines idiopathic hypersomnia as EDS without narcolepsy or the associated features of other sleep disorders. It occurs in the absence of medical problems or sleep disruptions, such as sleep apnea, that can cause secondary hypersomnia.
Signs and symptoms
This section needs additional citations for verification. (June 2021)
- Excessive daytime sleepiness, characterized by persistent sleepiness throughout the day and often a general lack of energy—even during the day after apparently adequate or even prolonged nighttime sleep. People with EDS nap repeatedly throughout the day and have strong urges to sleep while driving, working, eating, or conversing with others.
- Sleep inertia (also known as sleep drunkenness), characterized by having extreme difficulty waking up and feeling an uncontrollable desire to go back to sleep.
- Clouding of consciousness characterized by inattention, thought process abnormalities, comprehension abnormalities, and language abnormalities. These symptoms may affect performance on perception, memory, learning, executive functions, language, constructive abilities, voluntary motor control, attention, and mental speed. Sufferers can complain of forgetfulness, confusion, or inability to think clearly.
- Excessive sleep (9 hours or more over a full 24-hour period), without feeling refreshed after waking. Daytime naps can be up to several hours and are also unrefreshing.
Some studies have shown increased frequencies of palpitations, digestive problems, difficulty with body temperature regulation, and other symptoms in patients with IH. Anxiety and depression are frequent, likely as a response to chronic illness. A case series in 2010 found that peripheral vascular symptoms, such as cold hands and feet (e.g., Raynaud Syndrome), were more common in people with IH than in controls.
Other autonomic dysfunctional symptoms, such as fainting episodes, dizziness upon arising, headaches (possibly migrainous in quality), food cravings, and impotence may also be correlated with IH. Researchers have found that people reporting IH symptoms report high levels of autonomic dysfunction on par with other conditions of autonomic failure (i.e., MSA and diabetes). As of June 2021[update], there is no evidence to suggest such symptoms are related to IH in any way.
Unlike narcolepsy with cataplexy, which has a known cause (autoimmune destruction of hypocretin-producing neurons), the cause of IH is largely unknown. As of 2012[update], researchers have identified a few abnormalities associated with IH, which with further study may help to clarify the etiology.
Destruction of noradrenergic neurons has produced hypersomnia in experimental animal studies, and injury to adrenergic neurons has also been shown to lead to hypersomnia. IH has also been associated with a malfunction of the norepinephrine system and decreased cerebrospinal fluid (CSF) histamine levels.
Researchers have recently found an abnormal hypersensitivity to GABA (the major brain chemical responsible for sedation) in a subset of patients with central hypersomnia i.e.: IH, narcolepsy without cataplexy and long sleepers. They have identified a small (500 to 3000 daltons) naturally occurring bioactive substance (most likely a peptide as it is trypsin-sensitive) in the CSF of afflicted patients. Although this substance requires further identification of its chemical structure, it is currently referred to as a "somnogen" because it has been shown to cause hyper-reactivity of GABAA receptors, which leads to increased sedation or somnolence. In essence, it is as though these patients are chronically sedated with a benzodiazepine (medication which acts through the GABA system) such as Versed or Xanax, even though they do not take these medications.
People with IH often live without a correct diagnosis for a long time, blaming themselves and struggling to maintain work, studies, and relationships. IH has historically been difficult to diagnose at an early stage, especially due to low awareness and therefore, at the time of presentation, most patients have had the disorder for many years.
IH lacks a clearly defining biological marker like HLA-DQB1*0602 genotype in narcolepsy. Doctors can more carefully exclude these causes of EDS in order to more correctly diagnose IH. However, "even in the presence of other specific causes of hypersomnia, one should carefully assess the contribution of these etiological factors to the complaint of EDS and when specific treatments of these conditions fail to suppress EDS, the additional diagnosis of IH should be considered."
The severity of EDS can be quantified by subjective scales, such as the Epworth Sleepiness Scale and the Stanford Sleepiness Scale, and also by objective tests, like actigraphy, psychomotor vigilance task, maintenance of wakefulness test (MWT), multiple sleep latency test (MSLT) although as per latest research studies, the effectiveness of MSLT has been called into question. Several groups of researchers have found normal MSLT results in patients who otherwise seem to have IH. Therefore, when IH is suspected, researchers suggest appending a 24-hour continuous polysomnography to the standard overnight/MSLT study in order to record total sleep time.
The recent studies have also found that reports of sleepiness in IH relate more to mental fatigue rather than physiological sleepiness per se and the subjective scales like ESS, IH symptom diary (IHSD) and PGIC better captures the severity of symptoms consistently.
It is also important to note that whereas narcolepsy is strongly associated with the HLA-DQB1*0602 genotype, "HLA typing is of no help in the positive diagnosis of idiopathic hypersomnia." This is "despite some reports that suggest an increase [sic] frequency of HLA Cw2 and DRS in idiopathic hypersomnia subjects."
In patients with IH, polysomnography typically shows short sleep latency, increased mean slow wave sleep, and a high mean sleep efficiency. "Latency to REM sleep and percentages of light sleep and REM sleep were normal, compared with normal ranges." Despite this, one study has found increased sleep fragmentation in patients with IH without long sleep time, suggesting multiple possible presentations.
- Daytime lapses into sleep or an irrepressible need to sleep on a daily basis, for at least 3 months
- Absence of insufficient sleep syndrome
- Absence of cataplexy
- Absence of other causes of hypersomnia
- The presence of positive MSLT tests.
The latest ICD 10 defines IH with long sleep time as a neurological disorder that is a rare sleep disorder characterized by prolonged sleep at night and extreme sleepiness during the day. There are no apparent causes. This disorder affects the ability to function. It is of central nervous system origin characterized by prolonged nocturnal sleep and periods of daytime drowsiness. Affected individuals experience difficulty with awakening in the morning and may have associated sleep drunkenness, automatic behaviors, and memory disturbances. This condition differs from narcolepsy in that daytime sleep periods are longer, there is no association with cataplexy, and the multiple sleep latency onset test does not record sleep-onset rapid eye movement sleep.
Since the underlying mechanism is not yet fully understood, treatment efforts have usually focused on symptom management. In August 2021, low-sodium oxybate (Xywav) became the first U.S. FDA-approved treatment for idiopathic hypersomnia (IH). www.hypersomniafoundation.org/treatments. Wake-promoting medications used in narcolepsy are also commonly used off-label to help manage the excessive daytime sleepiness of IH. However, the medications currently used for IH are far from satisfactory. CNS stimulants tend to be less effective for IH than they are for narcolepsy and may be less well tolerated. Different medications could be administered in combination to address different symptoms like it is found that methylphenidate is effective in addressing EDS while pemoline is more effective in addressing brain fog.
The main treatment of excessive daytime sleepiness is done through central nervous system stimulants.
Methylphenidate and Dextroamphetamine are most used stimulants to controlled EDS. Increased dopamine release is felt to be the main property explaining wake-promotion from these medications. Insomnia is another common side effect and may require additional treatment.
Non-stimulant wake-promoting medications
Solriamfetol is the first and only dual-acting dopamine and norepinephrine reuptake inhibitor approved by the FDA to improve wakefulness in adults living with excessive daytime sleepiness associated with narcolepsy or obstructive sleep apnea.
Pitolisant, a selective histamine 3 (H3) receptor antagonist/inverse agonist, was approved by FDA during August 2019. It works by increasing the synthesis and release of histamine, a wake-promoting neurotransmitter in the brain.
Modafinil and Armodafinil elevate hypothalamic histamine levels, and they are known to bind to the dopamine transporter, thereby inhibiting dopamine reuptake. Modafinil can cause uncomfortable side effects, including nausea, headache, and a dry mouth for some patients, while other patients report no noticeable improvement even on relatively high dosages. They may also "interact with low-dose contraceptives, potentially reducing efficacy, although the scientific data supporting this claim is weak and rests on poorly documented anecdotes."
Sleep promoting medications
Sodium oxybate is an orphan drug which was designed specifically for the treatment of narcolepsy. Common side effects include nausea, dizziness, and hallucinations. A 2016 study by Leu-Semenescu et al. found sodium oxybate reduced daytime sleepiness in IH to the same degree as in patients with narcolepsy type 1, and the drug improved severe sleep inertia in 71% of the hypersomnia patients. In July 2020, the FDA approved Xywav™ (calcium, magnesium, potassium, and sodium oxybates), an oral solution for the treatment of cataplexy or excessive daytime sleepiness (EDS) in patients 7 years of age and older with narcolepsy.
Cognitive Behavioral Therapy (CBT)
In addition to medications, "behavioral approaches and sleep hygiene techniques are recommended, although they have little overall positive impact on this disease." "Planned naps are unhelpful, as they are both long and unrefreshing." Although behavioral approaches have not been shown to improve EDS, the goal, as in CBT (cognitive behavioral therapy), is often to help patients learn to reduce their negative emotional responses (e.g. frustration, anger, depression) to their disease symptoms. Furthermore, because IH "may lead to marriage breakdown, extensive counseling for the patient's partners, educating them about the symptomatology and treatment options, must be part of a comprehensive management plan. Education of relatives, friends, and colleagues helps the patient to function much better with this incurable disease."
IH is a lifelong disorder (with only rare spontaneous remissions). Symptoms typically begin in adolescence or young adulthood. It is often initially progressive as it reaches its peak and then stabilizes. Once stable, at times it may appear as though symptoms have worsened however this is more likely to be due to other factors such as other illness, stress or lifestyle demands that have made the IH symptoms more difficult to manage. It is therefore important that people with IH take good care of their overall physical and mental wellbeing. IH’s main consequences are professional and social.
The disorder is chronic, and the symptoms can be relentless. If an effective medication to control symptoms cannot be found, it can be extremely difficult for people with IH to hold down jobs, remain in school, maintain marriages, and fully engage with their family and friends. Even with medication, patients may struggle with these activities. Many patients are chronically tardy to work, school or social engagements and, over time, may lose the ability to function in family, social, occupational or other settings altogether.
IH profoundly affects work, education, and quality of life. Patients often need to drastically adapt their lifestyle after diagnosis, avoiding situations that might be dangerous while sleepy, such as driving. Patients are often too sleepy to work or attend school regularly, and they are predisposed "to develop serious performance decrements in multiple areas of function as well as to potentially life-threatening domestic, work-related and driving accidents." Furthermore, these risks are higher for IH patients than for those with sleep apnea or severe insomnia. In fact, "the most severe cases of daytime somnolence are found in patients affected by narcolepsy or IH." Surprisingly, excessive daytime sleepiness is even more handicapping than the cataplectic attacks of narcolepsy.
Due to the consequences of their profound EDS, both IH and narcolepsy can often result in unemployment. Several studies have shown a high rate of unemployment in narcoleptics (30–59%), which was felt to be related to the severe symptoms of their illness.
Typically, the symptoms of IH begin in adolescence or young adulthood, although they can begin at a later age. After onset, hypersomnia often worsens over several years, but it is often stable by the time of diagnosis and appears to be a lifelong condition. Spontaneous remission is only seen in 10–15% of patients.
According to the limited epidemiological data that exists, IH "has more of a female preponderance (1.8/1)." Family cases are frequent, in a range from 25% to 66% without any clear mode of inheritance."
IH has long been considered a rare disease, believed to be 10 times less frequent than narcolepsy. The prevalence of narcolepsy (with cataplexy) is estimated between 1/3,300 and 1/5,000. Although the true prevalence of IH is unknown, it is estimated at 1/10,000 to 1/25,000 for the long sleep form and 1/11,000 to 1/100,000 without long sleep. A more precise estimate "is complicated by a lack of clear biologic markers" and a lack of "unambiguous diagnostic criteria."
Because IH has been considered a rare disease, it has not received enough attention from authorities and researchers. "Patients are rare, researchers and scientists involved in the field are few and research findings are therefore scarce." "In Europe and in North America there is now a public health concern about helping patients and families affected by these rare diseases. Due to the complexity of the disease, they often experience difficulties to be diagnosed and often face social and professional consequences." (see Prognosis)
Society and culture
IH is a rarity in the public eye and has a very low level of public awareness.
Because of this low awareness, patients with IH often need significant support because they are at risk of being isolated and misunderstood. Therefore, the education of relatives, friends, and colleagues helps the patient to function much better with this incurable disease.
There is ongoing research into the efficacy of gamma aminobutyric acid A (GABAA) receptor antagonists for the treatment of IH. Research findings suggest that the GABA neurotransmitter system plays a significant role in the etiology of primary hypersomnias, such as IH and Narcolepsy Type 2. Given the possible role of hyperactive GABAA receptors in IH, medications that could counteract this activity are being studied to test their potential to improve sleepiness. These currently include clarithromycin and flumazenil.
Flumazenil, a GABAA receptor antagonist is approved by the FDA for use in anesthesia reversal and benzodiazepine overdose. Research has shown that flumazenil provides relief for most patients whose CSF contains the unknown "somnogen" that enhances the function of GABAA receptors, making them more susceptible to the sleep-inducing effect of GABA. For one patient, daily administration of flumazenil by sublingual lozenge and topical cream has proven effective for several years. A 2014 case report also showed improvement in IH symptoms after treatment with a continuous subcutaneous flumazenil administration. The patient was treated with a short-term subcutaneous administration through 96-hour continuous low dose (4 mg/day) infusion of flumazenil, followed by a slow-release long term subcutaneous administration through flumazenil implant.
Clarithromycin, an antibiotic approved by the FDA for the treatment of infections, was found to return the function of the GABA system to normal in patients with IH. In the pilot study, clarithromycin improved subjective sleepiness in GABA-related hypersomnia. In 2013, a retrospective review evaluating longer-term clarithromycin use showed efficacy in a large percentage of patients with GABA-related hypersomnia.
Dr. Ferini-Strambi and his colleagues in Milan, Italy, performed neurologic examinations by applying anodal tDCS by placing one electrode over the left dorsolateral prefrontal cortex, with the cathode over the contralateral orbit over 3 weeks period and found that seven of the eight participants (87.5%) reported improvement in their daytime sleepiness, including for up to two weeks after the end of the study.
Neural networks that regulate arousal and sleep comprise a bottom-up (from the brainstem to the cortex) pathway and a top-down (corticothalamic) pathway. The bottom-up pathway emerges from the ascending reticular arousal system (ARAS) and activates the cortex via well-characterized thalamic and nonthalamic pathways through cholinergic and aminergic neurotransmission. The bottom-up pathway represents the leverage point for pharmaceutical interventions. It is complemented by a corticothalamic top-down pathway, which appears to be modifiable through noninvasive brain stimulation (NIBS) techniques. A single case report study indicates that high-frequency repetitive transcranial magnetic stimulation (HF rTMS) over the left dorsolateral prefrontal cortex (DLPFC) might represent an alternative choice for symptom control in narcoleptic patients with cataplexy. rTMS may also exert intrinsic effects on hypersomnia in depressed adolescents.
Selegiline, monoamine oxidase type B (MAO-B) inhibitor works by slowing the breakdown of certain substances in the brain (mostly dopamine, but also serotonin and norepinephrine). It may also be useful, as it is also a metabolic precursor of amphetamine and exerts most of its therapeutic effects through amphetamine metabolism. It is not commonly prescribed for people with narcolepsy because of the high dosage required and potential for severe side effects.
Atomoxetine (or reboxetine in Europe) is an adrenergic reuptake inhibitor which increases wakefulness (generally less strongly than the medications which act on dopamine) and which has been argued to have a "clear use in the therapeutic arsenal against narcolepsy and hypersomnia although undocumented by clinical trials."
Ritanserin is a serotonin antagonist that has "been shown to improve daytime alertness and subjective sleep quality in patients on their usual narcolepsy medications." It is intended as an adjunct (supplement to another main therapeutic agent), and although it is not available in the US, it is available in Europe.
Antidepressants seems to have some therapeutic effects as they enhance synaptic levels of noradrenaline and serotonin. Further, different medicines are known to augment the activity of one another like as seen in the case of Fluoxetine which augmented the activity of methylphenidate when taken together.
Bupropion, a norepinephrine-dopamine reuptake inhibitor (NDRI), which works by inhibiting the reabsorption of two important brain chemicals – norepinephrine and dopamine, is known to have wake-promoting effects.
Fluoxetine, an antidepressant of the selective serotonin reuptake inhibitor (SSRI) class is also known to have mild stimulating effects. It is also known to augment the activity of methylphenidate.
Caffeine is one of the safer nondopaminergic wake-promoting compounds. It is widely used but "has intolerable side effects at high doses (including cardiovascular), and it is generally not efficient enough for patients with hypersomnia or narcolepsy." Although it is commonly used by people with IH or narcolepsy, many people with these disorders report that it has only limited benefit on their sleepiness.
Melatonin is a hormone that the body produces to help regulate sleep. One small study, which used a dose of 2 mg slow-release melatonin at bedtime, found that 50% of participants had “shortened nocturnal sleep duration, decreased sleep drunkenness and relieved daytime sleepiness.” Other studies have shown that melatonin synchronizes the circadian rhythms, and improves the “onset, duration and quality of sleep.”
There have been some studies suggesting levothyroxine as a possible treatment for IH, especially for patients with subclinical hypothyroidism. This treatment does carry potential risks (especially for patients without hypothyroidism or subclinical hypothroidism), which include cardiac arrhythmia.
Hypocretin-1 has been shown to be strongly wake-promoting in animal models, but it does not cross the blood-brain barrier. Suvorexant, a hypocretin receptor antagonist, has been developed to limit the natural effects of hypocretin in patients with insomnia. It is therefore possible that a hypocretin agonist may be similarly developed for the treatment of hypersomnia.
Antidepressants seems to have some therapeutic effects as they enhance synaptic levels of noradrenaline and serotonin and for same reason enhancing the levels of acetylcholine may have some therapeutic effect. Donepezil showed improvement in one patient by decreasing ESS score from 20 up to 14. Memantine has also shown some positive effect on a patient suffering from narcolepsy.
Levodopa is an amino acid and is the precursor to the neurotransmitters dopamine, norepinephrine (noradrenaline), and epinephrine (adrenaline). As per a study of six narcoleptic patients it was found that L-dopa improved vigilance and performance as evaluated by the AVS and the FCRTT, while the capacity to fall asleep rapidly remained unchanged as evaluated by the MSLT. It raises the hypothesis that dopamine may play a role in the physiopathology of excessive daytime sleepiness of this condition.
Carnitine, has also been shown to improve narcolepsy symptoms (including daytime sleepiness) by increasing fatty-acid oxidation. Abnormally low levels of acylcarnitine have been observed in patients with narcolepsy. These same low levels have been associated with primary hypersomnia in general in mouse studies. "Mice with systemic carnitine deficiency exhibit a higher frequency of fragmented wakefulness and rapid eye movement (REM) sleep, and reduced locomotor activity." Administration of acetyl-L-carnitine was shown to improve these symptoms in mice. A subsequent human trial found that narcolepsy patients given L-carnitine spent less total time in daytime sleep than patients who were given placebo.
- Narcolepsy and hypersomnia: review and classification of 642 personally observed cases. Roth B. Schweiz Arch Neurol Neurochir Psychiatr. 1976;119(1):31-4
- "International classification of sleep disorders, revised: Diagnostic and coding manual" (PDF). American Academy of Sleep Medicine. 2001. Archived from the original (PDF) on 26 July 2011. Retrieved 25 January 2013.
- "Medscape Overview#aw2aab6b2b5". Retrieved 2013-01-25.
- Bayon V, Léger D, Philip P (2009). "Socio-professional handicap and accidental risk in patients with hypersomnias of central origin". Sleep Med Rev. 13 (6): 421–426. doi:10.1016/j.smrv.2009.02.001. PMID 19493688.
- Diagnostic and statistical manual of mental disorders : DSM-IV-. Washington, DC: American Psychiatric Association. 2000. ISBN 0-89042-025-4.
- Trotti, LM (September 2017). "Idiopathic Hypersomnia". Sleep Medicine Clinics. 12 (3): 331–344. doi:10.1016/j.jsmc.2017.03.009. PMC 5558858. PMID 28778232.
- "Idiopathic hypersomnia | Genetic and Rare Diseases Information Center (GARD) – an NCATS Program". rarediseases.info.nih.gov.
- "About Idiopathic Hypersomnia". Hypersomnia Foundation.
- John Noble; Harry L. Greene (1996). Textbook of Primary Care Medicine. Mosby. p. 1325.
- Bassetti, C (1997). "Idiopathic hypersomnia A series of 42 patients". Brain. 120 (8): 1423–1435. doi:10.1093/brain/120.8.1423. PMID 9278632.
- Vernet C, Leu-Semenescu S, Buzare MA, Arnulf I (2010). "Subjective symptoms in idiopathic hypersomnia: beyond excessive sleepiness". Journal of Sleep Research. 19 (4): 525–534. doi:10.1111/j.1365-2869.2010.00824.x. PMID 20408941. S2CID 26085500.
- Billiard, M.; Dauvilliers, Y. (Oct 2001). "Idiopathic Hypersomnia". Sleep Med Rev. 5 (5): 349–358. doi:10.1053/smrv.2001.0168. PMID 12530998.
- Kim, Paul; Cheung, Joseph; Schneider, Logan; Trotti, LynnMarie; Miglis, Mitchell (9 April 2019). "Autonomic Symptom Burden in Idiopathic Hypersomnia (S46.005)". Neurology. 92 (15 Supplement). ISSN 0028-3878.
- Mignot, Emmanuel J. M. (2012). "A Practical Guide to the Therapy of Narcolepsy and Hypersomnia Syndromes". Neurotherapeutics. 9 (4): 739–52. doi:10.1007/s13311-012-0150-9. PMC 3480574. PMID 23065655.
- Preda, Adrian. "Primary Hypersomnia: Etiology". Medscape. Retrieved 25 January 2013.
- Lynn Marie Trotti, MD (August 9, 2010). "Flumazenil for the Treatment of Primary Hypersomnia". Emory University – Georgia Research Alliance. ClinicalTrials.gov. Retrieved 2013-01-25.
- Lynn Marie Trotti, MD (June 15, 2010). "Clarithromycin for the Treatment of Primary Hypersomnia". Emory University – Georgia Research Alliance. ClinicalTrials.gov. Retrieved 2013-01-25.
- Montplaisir J, Fantini L (2001). "Idiopathic hypersomnia: a diagnostic dilemma. A commentary of "Idiopathic hypersomnia" (M. Billiard and Y. Dauvilliers)". Sleep Med Rev. 5 (5): 361–362. doi:10.1053/smrv.2001.0216. PMID 12530999.
- "Maintenance of Wakefulness Test". Hypersomnia Foundation.
- Dauvilliers, Yves; et al. (2006-04-01). "Differential Diagnosis in Hypersomnia". Current Neurology and Neuroscience Reports. Current Medicine Group. 6 (2): 156–162. doi:10.1007/s11910-996-0039-2. PMID 16522270. S2CID 43410010.
- "Quantifying sleepiness". Retrieved 2013-07-23.
- Michel Billiard, MD. "Idiopathic Hypersomnia". Sleep Disorders I. Gui-de-Chauliac Hospital, Neurology B Department, 34295 Montpellier, Cedex 05, France. pp. 573–582.
- Roth, T.; Dorenbaum, A.; Jaros, M.; Lam, M. (2019-12-01). "Are reports of mental fog from patients with idiopathic hypersomnia mediated by objective measures of daytime sleepiness?". Sleep Medicine. 64: S328. doi:10.1016/j.sleep.2019.11.917.
- Anderson (2007). "Idiopathic hypersomnia: A study of 77 Cases". Sleep. 30 (10): 1274–81. doi:10.1093/sleep/30.10.1274. PMC 2266276. PMID 17969461.
- Pizza (2007). "Polysomnographic study of nocturnal sleep in idiopathic hypersomnia without long sleep time". Journal of Sleep Research. 22 (2): 185–96. doi:10.1111/j.1365-2869.2012.01061.x. PMID 23061443. S2CID 205353142.
- https://www.hypersomniafoundation.org/document/ihsummary/. Missing or empty
- "About Idiopathic Hypersomnia".
- "Classification of Hypersomnias". Hypersomnia Foundation.
- "2021 ICD-10-CM Diagnosis Code G47.11: Idiopathic hypersomnia with long sleep time". www.icd10data.com.
- "Epocrates – Adderall". Retrieved 2013-07-19.
- "Jazz Pharmaceuticals Announces U.S. FDA Approval of Sunosi™ (solriamfetol) for Excessive Daytime Sleepiness Associated with Narcolepsy or Obstructive Sleep Apnea | Jazz Pharmaceuticals plc". investor.jazzpharma.com.
- Ishizuka T, Murakami M, Yamatodani A (January 2008). "Involvement of central histaminergic systems in modafinil-induced but not methylphenidate-induced increases in locomotor activity in rats". Eur. J. Pharmacol. 578 (2–3): 209–15. doi:10.1016/j.ejphar.2007.09.009. PMID 17920581.
- "Epocrates – Provigil". Retrieved 2013-01-29.
- "Epocrates – Xyrem". Retrieved 2013-01-29.
- Leu-Semenescu Smaranda, Louis Pauline, Arnulf Isabelle (2016). "Benefits and risk of sodium oxybate in idiopathic hypersomnia versus narcolepsy type 1: a chart review". Sleep Medicine. 17: 38–44. doi:10.1016/j.sleep.2015.10.005. PMID 26847972.CS1 maint: multiple names: authors list (link)
- "Jazz Pharmaceuticals Announces U.S. FDA Approval of Xywav™ (calcium, magnesium, potassium, and sodium oxybates) Oral Solution for Cataplexy or Excessive Daytime Sleepiness Associated with Narcolepsy | Jazz Pharmaceuticals plc". investor.jazzpharma.com.
- "Medscape – Treatment". Retrieved 2013-01-25.
- "Primary Hypersomnia". Retrieved 2013-01-29.
- D.B. Rye; D.L. Bliwise; K. Parker; L.M. Trotti; P. Saini; J. Fairley; A. Freeman; P.S. Garcia; M.J. Owens; J.C. Ritchie; A. Jenkins (2012). "Modulation of Vigilance in the Primary Hypersomnias by Endogenous Enhancement of GABAA Receptors". Sci. Transl. Med. 4 (161): 161ra151. doi:10.1126/scitranslmed.3004685. PMID 23175709. S2CID 44236050.
- Gosmany M (1998). "The influence of clinical symptoms on quality of life in patients with narcolepsy". Neurology. 50 (2 Suppl 1): S31–6. doi:10.1212/wnl.50.2_suppl_1.s31. PMID 9484421. S2CID 5872229.
- Dodel R, Peter H, Walbert T, Spottke A, Noelker C, Berger K, et al. (2004). "The socio-economic impact of narcolepsy". Sleep. 27 (6): 1123–8. doi:10.1093/sleep/27.6.1123. PMID 15532206.
- National Institutes of Health (June 2008). "NINDS Hypersomnia Information Page". Archived from the original on 2012-04-06. Retrieved 2009-01-23.
- Billiard, Michel; Sonka, Karel (2016). "Idiopathic hypersomnia". Sleep Medicine Reviews. 29: 23–33. doi:10.1016/j.smrv.2015.08.007. ISSN 1087-0792. PMID 26599679.
- Mallampalli, Monica P.; Carter, Christine L. (2014). "Exploring Sex and Gender Differences in Sleep Health: A Society for Women's Health Research Report". Journal of Women's Health. 23 (7): 553–562. doi:10.1089/jwh.2014.4816. ISSN 1540-9996. PMC 4089020. PMID 24956068.
- "Narcolepsy-cataplexy". Retrieved 2014-08-14.
- "Idiopathic hypersomnia". Retrieved 2014-08-14.
- "Primary hypersomnia epidemiology". Retrieved 2014-08-14.
- "A Randomized, Placebo-Controlled, Double-Blind, Crossover Study of Oral BTD-001 in Adults with Idiopathic Hypersomnia". 28 April 2020. Cite journal requires
- Pickrell K. L., Richards R. K. (1945). "Pentothal-metrazol antagonism : a method of shortening the recovery period following pentothal anesthesia a clinical and experimental study". Ann Surg. 121 (4): 495–506. doi:10.1097/00000658-194504000-00009. PMC 1618127. PMID 17858587.
- E. Kelty; V. Martyn; G. O'Neil; G. Hulse (19 February 2014). "Use of subcutaneous flumazenil preparations for the treatment of idiopathic hypersomnia: A case report". Journal of Psychopharmacology. 28 (7): 703–706. doi:10.1177/0269881114523865. PMID 24554692. S2CID 31846588.
- Trotti, L; et al. (June 2013). "CLARITHROMYCIN FOR THE TREATMENT OF HYPERSOMNIA: A RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED, CROSSOVER TRIAL". Sleep. 36 (Abstract Supplement): A248.
- Trotti, L; et al. (December 3, 2013). "Improvement in daytime sleepiness with clarithromycin in patients with GABA-related hypersomnia: Clinical experience". Journal of Psychopharmacology. 28 (7): 697–702. doi:10.1177/0269881113515062. PMID 24306133. S2CID 13121904.
- "A Pilot Study of tDCS Looks Promising for the Treatment of IH". Hypersomnia Foundation. 1 November 2016.
- Galbiati, Andrea; Abutalebi, Jubin; Iannaccone, Sandro; Borsa, Virginia Maria; Musteata, Stela; Zucconi, Marco; Giora, Enrico; Ferini-Strambi, Luigi (1 April 2016). "The effects of Transcranial Direct Current Stimulation (tDCS) on Idiopathic Hypersomnia: a pilot study". Archives Italiennes de Biologie. 154 (1): 1–5. doi:10.12871/00039829201611. ISSN 0003-9829. PMID 27548094.
- Krone, Lukas; Frase, Lukas; Piosczyk, Hannah; Selhausen, Peter; Zittel, Sulamith; Jahn, Friederike; Kuhn, Marion; Feige, Bernd; Mainberger, Florian; Klöppel, Stefan; Riemann, Dieter; Spiegelhalder, Kai; Baglioni, Chiara; Sterr, Annette; Nissen, Christoph (NaN). "Top-down control of arousal and sleep: Fundamentals and clinical implications". Sleep Medicine Reviews. 31: 17–24. doi:10.1016/j.smrv.2015.12.005. ISSN 1532-2955. PMID 26883160. Check date values in:
- Nardone, Raffaele; Sebastianelli, Luca; Versace, Viviana; Brigo, Francesco; Golaszewski, Stefan; Pucks-Faes, Elke; Saltuari, Leopold; Trinka, Eugen (1 July 2020). "Effects of repetitive transcranial magnetic stimulation in subjects with sleep disorders". Sleep Medicine. 71: 113–121. doi:10.1016/j.sleep.2020.01.028. ISSN 1389-9457. PMID 32173186.
- Adenuga, Olufemi; Attarian, Hrayr (2014). "Treatment of Disorders of Hypersomnolence". Current Treatment Options in Neurology. 16 (9): 302. doi:10.1007/s11940-014-0302-9. ISSN 1092-8480. PMID 25080137. S2CID 207342823.
- Andrade, Chittaranjan (1999). "Primary hypersomnia : Response to fluoxetine and methylphenidate". Indian Journal of Psychiatry. 41 (4): 377–380. ISSN 0019-5545. PMC 2963848. PMID 21430816.
- "Successful treatment with levothyroxine for idiopathic hypersomnia patients with subclinical hypothyroidism". General Hospital Psychiatry – Elsevier Inc. Retrieved 2010-08-05.
- H. Shinno et al. (June 2011). "Effect of levothyroxine on prolonged nocturnal sleep time and excessive daytime somnolence in patients with idiopathic hypersomnia." Sleep Medicine Vol. 12 6: 578–583
- "Epocrates – levothyroxine". Retrieved 2013-01-29.
- Niederhofer, Helmut (15 January 2006). "Donepezil in the treatment of narcolepsy". Journal of Clinical Sleep Medicine. 2 (1): 71–72. doi:10.5664/jcsm.26438. ISSN 1550-9389. PMID 17557440.
- Niederhofer, Helmut (1 October 2010). "Memantine also effective in a patient suffering from narcolepsy?". Sleep and Biological Rhythms. 8 (4): 228. doi:10.1111/j.1479-8425.2010.00453.x. ISSN 1479-8425. S2CID 145515017.
- Boivin, D. B.; Montplaisir, J. (August 1991). "The effects of L-dopa on excessive daytime sleepiness in narcolepsy". Neurology. 41 (8): 1267–1269. doi:10.1212/wnl.41.8.1267. ISSN 0028-3878. PMID 1866017. S2CID 11487907.
- "Summary of Rationale Behind and Research Studies into L-carnitine as a Treatment for Narcolepsy". Hypersomnia Foundation. 19 January 2016.
- Miyagawa T, Miyadera H, Tanaka S, Kawashima M, Shimada M, Honda Y, Tokunaga K, Honda M (March 2011). "Abnormally low serum acylcarnitine levels in narcolepsy patients". Sleep. 34 (3): 349–353. doi:10.1093/sleep/34.3.349. PMC 3041711. PMID 21358852.
- Miyagawa T, Honda M, Kawashima M, Shimada M, Tanaka S, et al. (30 April 2009). Rubinsztein DC (ed.). "Polymorphism Located between CPT1B and CHKB, and HLA-DRB1*1501-DQB1*0602 Haplotype Confer Susceptibility to CNS Hypersomnias (Essential Hypersomnia)". PLOS ONE. 4 (4): e5394. Bibcode:2009PLoSO...4.5394M. doi:10.1371/journal.pone.0005394. PMC 2671172. PMID 19404393.
- Miyagawa, T; Kawamura, H; Obuchi, M; Ikesaki, A; Ozaki, A; Tokunaga, K; Inoue, Y; Honda, M (2013). "Effects of oral L-carnitine administration in narcolepsy patients: A randomized, double-blind, cross-over and placebo-controlled trial". PLOS ONE. 8 (1): e53707. Bibcode:2013PLoSO...853707M. doi:10.1371/journal.pone.0053707. PMC 3547955. PMID 23349733.