Narcolepsy is a clinical syndrome of daytime sleepiness, cataplexy (sudden bilateral loss of muscle tone), hypnagogic hallucinations, and sleep paralysis. Only one-third of patients will have all of these classical findings.

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Epidemiology: The prevalence of Narcolepsy type 1 is 25 to 50 per 100,000 people. The incidence rate is highest in the second decade. The disorder is equally common in men and women. The onset associated with nonspecific environmental factors, such as head trauma, stroke, and change in sleep-wake cycle. 

Etiology: Narcolepsy Type 1 results from the loss of the neuropeptides orexin (hypocretin), which promote wakefulness and in regulating of the sleep-wake cycles. 

Secondary narcolepsy: lesions of the posterior hypothalamus and mid brain can cause narcolepsy. Most likely due to direct injury to the orexin neurons.

Clinical Presentation:

1-Daytime sleepiness: all patients with narcolepsy have chronic sleepiness. They are prone to fall asleep throughout the day, often at inappropriate times. The sleepiness may be so severe that patients with narcolepsy can doze off with little warning; these episodes are the “sleep attacks”. Sleepiness associated with narcolepsy usually improves temporarily after a brief nap, and most patients feel rested when they awake in the morning.

2-Cataplexy: It is emotionally triggered transient muscle weakness. The muscle weakness is often partial, affecting the face, neck, and knees. Severe episodes can induce bilateral weakness or paralysis, causing the patient to collapse. Consciousness remains intact during cataplexy, and the weakness usually resolve in less than two minutes

3-Hypnagogic hallucinations: Which are vivid, often frightening visual, tactile, or auditory hallucinations that occur as the patient is falling asleep. 

4-Sleep paralysis : Sleep paralysis is the complete inability to move for one or two minutes immediately after awakening. Read more…

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HYPERSOMNIA

What is Hypersomnia?

Many people feel drowsy in early afternoon and they have a desire for a quick nap. This is probably normal and different from excessive daytime sleepiness, which is a much more significant problem. Hypersomnia is a disorder of excessive sleepiness as evidenced by either prolonged sleep episodes or daytime sleep episodes that occur almost daily and will cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.

What is Causing Excessive Daytime Sleepiness?

The prevalence of excessive daytime sleepiness, reported by up to 30% of the adult population.

Sleep Deprivation

By far, the most common cause of excessive daytime sleepiness in modern society is chronic sleep deprivation. Healthy adults can require anywhere from 4 to 10 hours of sleep. Therefore, people who need 8 hours of sleep a night but receive only 6 hours may become severely sleep deprived and notably hyper somnolent.

Primary Hypersomnia

Is excessive sleepiness for at least 1 month and is not related to other mental disorder or direct physiological effects of a substance (eg, drug of abuse, medication). 

Excessive daytime sleepiness leading to prolonged naps that are not refreshing, nocturnal sleep of long duration (as much as 12 h or more) and sleep drunkenness. These patients do not feel refreshed following naps and, therefore, fight sleepiness as long as they are able. Patients are difficult to awaken from sleep or naps.

Before a diagnosis of primary hypersomnia, all other causes of hypersomnia, should be excluded, so elimination of other causes of excessive daytime somnolence helps diagnose primary hypersomnia

Medication-Induced Hypersomnia

Certain agents may cause true hypersomnia. sedative-hypnotic agents, such as barbiturates, benzodiazepines and Many medications such as tricyclic antidepressants and antihistaminic agents may cause drowsiness.

Other Medical Conditions May Cause Hypersomnia

• Obstructive sleep apnea

• Posttraumatic hypersomnia

• Brain tumors

• Metabolic disorder such as hypothyroidism

• Seizure disorder

• Hydrocephalus

• Depression

What is the Appropriate Diagnostic Approach for Hypersomnic Patient?

All patients with chronic daytime sleepiness should have a thorough history, sleep history, physical exam, and neurological exam seeking evidence of cataplexy, hypnagogic, hypnopompic hallucinations, or sleep paralysis.

1*Subjective measures of excessive daytime sleepiness can be measured by The Epworth Sleepiness scale.  It is a self-administered questionnaire in which patients rate their likelihood of falling asleep in eight different life situations each situation is scored on scale from 0 (not at all likely to fall asleep) to 3 (very likely to fall asleep). The resulting total score is between 0 and 24. Although what score constitutes abnormal sleepiness is controversial, total scores above 10 generally warrant investigation.                                

2*objective measures of excessive daytime sleepiness can be measured by all-night polysomnogram(PSG) followed up with multiple sleep latency testing (MSLT) the day after.

Read more about MSLT..

3-*Measurement of the concentration of orexin-A/hypocretin-1 in CSF is primarily a research tool, but it can be useful in certain clinical situations.

4*HLA testing is not a routine diagnostic testing for narcolepsy now.

5*Blood testing to exclude metabolic or endocrine disorder and to exclude anemia, in addition some genetic tests may help to direct you to the right diagnosis.

6*CT images for the brain to exclude pathological reason for the hypersomnia.

Treatment of Hypersomnia

1) Pharmacologic Treatment
Stimulant medications, such as modafinil (Provigil) an alpha1-agonist, has been used for several years to treat narcolepsy and hypersomnia.

Tricyclic antidepressant can treat cataplexy attacks. Such as clomipramine or a selective serotonin reuptake inhibitor (SSRI), most commonly fluoxetine, while for sleep paralysis we use imipramin and clomipramin.

2) Behavioral treatment including good sleep hygiene. Most patients improve if they maintain a regular sleep schedule, usually 7.5-8 hours of sleep per night, scheduled naps during the day also may help in addition avoiding shift work is essential.

3) Environmental treatments including safety during driving. Here are some suggestions to sleepy drivers  Read more…