Hypersomnolence (Hypersomnia)

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Hypersomnolence is characterized by recurrent episodes of excessive daytime sleepiness or prolonged nighttime sleep. It has previously been referred to as “hypersomnia,” but this name does not capture both components of its definition.

Rather than feeling tired due to lack of or interrupted sleep at night, persons with hypersomnolence are compelled to nap repeatedly during the day, often at inappropriate times such as during work, during a meal, or in the middle of a conversation. These daytime naps usually provide no relief from symptoms.



Patients often have difficulty waking from a long sleep and may feel disoriented. Other symptoms include:

increased irritation
decreased energy
slow thinking
slow speech
loss of appetite
memory difficulty
Some patients lose the ability to function in family, social, occupational, or other settings.

  • Some may have a genetic predisposition to hypersomnolence; in others, there is no known cause.
  • Hypersomnolence typically affects adolescents and young adults.
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