Excessive Daytime Sleepiness Disorders

Excessive Sleepiness

Excessive Daytime Sleepiness Disorders are a specific type of sleep disorders, whose core symptom is experiencing excessive sleepiness (ES) during the day.

Excessive Sleepiness

Excessive Sleepiness

Sleepiness is an internal state preceding sleep characterised by a subjective feeling of itching and burning eyes, difficulty in keeping the eyes wide open, a sensation of heaviness in the limbs, loss of initiative and a strong desire for sleep.

The person suffering from excessive sleepiness is aware of having a lower alertness and he/she tries to defeat it but without succeeding.

Secondary ES Disorders

ES can be a consequence of suffering from other disorders, such as:

  • sleep disorders: sleep apneas, insomnias, restless legs disorder, circadian rhythm sleep disorders;
  • a psychiatric condition: depression, …
  • medical condition;
  • medication/substance use.

Primary ES Disorders

Primary ES Disorders are caused by dysfunctions of the central nervous system.


Narcolepsy is a chronic neurologic disorder characterised by:

  • intense sleepiness during the day: the person lives in a constant predisposition to sleep;
  • recurrent, short, refreshing and not always wanted sleep attacks during the day: the attacks are very hard to resist and they can manifest in each moment of the day (while eating, driving,  speaking, ..). Usually they last 10-20 minutes.
  • disturbed night-time sleep: patients tend to wake up many times during the night;
  • cataplexy: partial or total sudden and reversible muscle weakness caused by intense emotions. Almost 70% of narcoleptic patients experience cataplexy. It implies intense consequences, as the patients tend to avoid all emotion-related stimuli in order to prevent the unpleasant attacks.
  • sleep paralysis: a temporary body paralysis while we are about to fall asleep or to wake up, experienced by 30/50% of narcoleptic patients. It is a very unpleasant sensation, as the person is fully awake but not able to move and very often it is accompanied by distressful hallucinations. It is caused by a REM-sleep intrusion into wake.
  • hypnagogic hallucinations: special hallucinatory states perceived when we are about to fall asleep or to wake up.

Idiopathic Hypersomnia

Idiopathic Hypersomnia is very similar to Narcolepsy but the auxiliary symptoms, such as cataplexy or hallucinations, are not present.

It is characterised by sleep attacks, less intense than the narcoleptic ones, but longer and not refreshing; night-time sleep is preserved, but people have difficulties in quickly shifting from sleep to wake.

Klein Levin Syndrome

Klein Levin Syndrome is a recurrent type of hypersomnia, characterised by an intense but temporary sleepiness that makes the person spend most hours of the day sleeping. In these periods, when the patient is not sleeping, he/she experiences compulsive megaphagia and hyper-sexuality. It tends to affect men more often than women. The episodes’ length is variable, but they tend to occur every 6/12 months.

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