Hypersomnia
Hypersomnia refers to a group of disorders in which the primary complaint is excessive daytime sleepiness (EDS). EDS is defined as an excess of uncontrolled sleep, occurring at inappropriate times. It appears in monotonous situations and may result in an increase in daily total sleep time without a significant feeling of restoration.
EDS can have serious personal, family or professional consequences, such as impaired driving and occupational activities, and reduced quality of life.
EDS has to last for at least three months to be part of the diagnosis.
Primary hypersomnia. Hypersomnia may start in the central nervous system:
Narcolepsy. A neurological disorder characterized by four symptoms:
1. Excessive daytime sleepiness (EDS): EDS is the main symptom and the first symptom to appear.
2. Cataplexy: A sudden and short loss of muscle tone, normally caused by strong emotions such as laughter or anger. The duration is short, ranging from a few seconds to several minutes. The person is aware of the event. Cataplexy often occurs within a year of the onset of narcolepsy. Sleep paralysis and hypnagogic hallucinations appear later.
3. Sleep paralysis: A sudden and brief loss of muscle tone as the person is falling asleep or waking up. Although the person is aware of the event, he/she is unable to move or speak.
4. Hypnagogic hallucinations: Vivid dreams as the person is falling asleep.
Narcolepsy is a rare condition. It the most common form of primary hypersomnia, prevalent in 0.5% of people. This sleep disorder is seen in people aged 5-55. The first signs usually appear before the age of 25 and diagnosis requires a polysomnography (PSG) to determine whether or not REM sleep occurs at sleep onset (a classic sign of narcolepsy, called SOREMPs). A multiple sleep latency test (MSLT) should be prescribed in addition to the PSG. The diagnosis of narcolepsy is based on a mean sleep latency of less than eight minutes with two or more SOREMPs and the presence of excessive daytime sleepiness.
The ICSD-II recognizes narcolepsy with or without cataplexy as two distinct sleep disorders.
Idiopathic hypersomnia (cause unknown)
A condition with excessive daytime sleepiness (EDS), with or without increased sleep at night. Patients with EDS and without increased sleep at night may have a mean sleep latency of less than eight minutes but with less than two SOREMPs. This differs from patients with narcolepsy (without cataplexy) because, despite the presence of EDS, they present with two or more SOREMPs. In the other case, patients present with EDS with increased sleep at night. Idiopathic hypersomnia may run in families.
Secondary hypersomnia. Hypersomnia can also be caused by another medical disorder, for which one of the main symptoms is excessive daytime sleepiness:
1. Sleep apnea
2. Limb movements
3. Circadian rhythm sleep disorders
4. Upper airway resistance syndrome (UARS): A clinical syndrome for which the main symptom is excessive daytime sleepiness and results from RERA
5. Attention-deficit hyperactivity disorder: A development disorder seen in children and adults. The associated symptoms include impulsiveness, excessive agitation, low perseverance in non‑stimulating situations and excessive daytime sleepiness.
How is narcolepsy treated?
Treatments for hypersomnia vary from one condition to the next and depend on the age of the person.
Narcolepsy: central nervous system stimulants (modafinil or methylphenidate in some cases), or antidepressants for cataplexy, may be prescribed, or nonpharmacological treatment may be recommended, including maintaining good sleep hygiene or planning short daytime naps to help delay the narcoleptic episodes.
NOTE: Medication used to treat cataplexy associated with narcolepsy can trigger or further exacerbate RBD, a primary parasomnia of REM sleep.
Sleep apnea: a positive airway pressure machine will be prescribed to treat sleep apnea in adults. In children, a tonsillectomy or adenoidectomy is more likely to be recommended.
Involuntary limb movements: medication will be prescribed.
Teenagers who are “long sleepers” or shift workers: exposure to light or even chronotherapy (to reset their circadian rhythm) will be recommended in addition to the institution of good sleep hygiene measures.
Consult your physician to find the right treatment for your condition.
Signs of hypersomnia
Excessive daytime sleepiness
Fatigue
Hyperactivity
References:
Lévy, P., et al. “Sleep Disorders and Their Classification–An Overview.” Edited by WJ Randerath, BM Sanner, and VK Somers. In Sleep Apnea: Current Diagnosis and Treatment. Progress in Respiratory Research. Edited by CT Bolliger. Vol. 35, 2006.
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