Difference Between Hypersomnia and Narcolepsy

Sleep is an essential part of human life. It is a natural process that allows our body and mind to rest, recover and recharge for the next day. However, some people experience sleep disorders that disrupt their sleep patterns and make it difficult for them to get the rest they need.

Two common sleep disorders are hypersomnia and narcolepsy. While they share some similarities, there are key differences between the two. In this essay, we will explore the differences between hypersomnia and narcolepsy.

What is Hypersomnia?

Hypersomnia is a pathological condition characterized by unusual sleepiness. It can develop as a complication of the course of many diseases, most often diseases of the nervous system.

The main reasons for hypersomnia are −

  • Prolonged and regular lack of sleep;

  • Physical overload, mental overload;

  • Emotional shock and stress situations;

  • Medicines;

  • Skull trauma;

  • Tumors, intracerebral hematomas;

  • Infectious diseases (meningitis, encephalitis, syphilis);

  • Apnea and accompanying brain tissue hypoxia;

  • Mental disorders;

  • Endocrine disorders.

Some types of hypersomnia have an unknown etiology.

The main symptoms of the disease are excessive nighttime sleep (about 14 hours) and sleepiness during the day. Other characteristic signs are a difficult wakening in the morning, even with an alarm clock. In hypersomnia, the patient needs a long period to wake up.

This condition affects efficiency, attention, concentration, and greatly reduces working capacity. Even sleep during the day usually does not relieve the patient.

The diagnostic methods are −

  • Special tests (Stanford sleepiness scale, sleep latency test);

  • Electro-polygraphy or polysomnography of waking and night sleep;

  • Clinical evaluation of the somatic, mental and neurological status of the patient;

  • NMR of the brain;

  • Cerebrospinal fluid examination.

The differential diagnosis method is also used to exclude asthenia, chronic fatigue syndrome and other functional disorders with similar symptoms.

There are several types of hypersomnia −

  • Idiopathic hypersomnia;

  • Pathological hypersomnia;

  • Narcolepsy;

  • Post-traumatic hypersomnia;

  • Drug hypersomnia;

  • Klein-Levin syndrome;

In order to undertake adequate treatment of hypersomnia, it is important to determine the causes of the condition and to eliminate them. If it develops as an independent neuropsychiatric disorder, it should be treated medically and by regulating the patient’s sleep habits and diet.

What is Narcolepsy?

Narcolepsy is a chronic neurological disease characterized by excessive daytime sleepiness. The patients are unable to control the wakefulness and sudden sleep, regardless of circumstances and environment. It usually starts in childhood, but a clear clinic is expressed later.

Sleep can occur at any moment – while doing the usual day-to-day work at home or at work, even in hazardous circumstances such as driving and operating machinery. It only lasts a few minutes, with different frequencies during the day. Work and concentration are usually violated.

Other symptoms of narcolepsy are −

  • Temporary muscle paralysis when awakening;

  • Sleep or awakening causes hallucinations;

  • Sudden muscle weakness lasting seconds to several minutes;

  • Higher incidence of sleep disorders, such as insomnia, sleep apnea, restless legs syndrome, etc.;

  • Disturbed night sleep.

The cause of narcolepsy is unknown. Single inheritance cases are described, but there is often no occurrence in the family. Studies of individuals suffering from narcolepsy show very low levels of the neurotransmitter hypocretin. Hypocretin is considered to be involved in the sleep control at a hypothalamus level.

The diagnosis of narcolepsy is based on the characteristic clinical picture and some studies. Questionnaires are developed in an attempt to objectify the sleepiness during the day.

Of great importance is the analysis of the sleep through polysomnography. It monitors the cardiac function, biological activity of the brain, muscle tone, eye movements, and respiratory movements. The time necessary to fall asleep during the day in a lying position with a suitable atmosphere is also recorded.

There is no definitive treatment for narcolepsy. Stimulants are used to control sleepiness and stimulate performance. Antidepressants are used for cataplexy. Regular sleep at night is recommended – at specific time intervals, as well as breaks during the day.

Differences: Hypersomnia and Narcolepsy

One of the main differences between hypersomnia and narcolepsy is the timing of sleepiness. People with hypersomnia generally feel excessively sleepy throughout the day, whereas people with narcolepsy experience sudden, unexpected episodes of sleepiness. Hypersomnia is often caused by factors such as poor sleep hygiene or medical conditions, while narcolepsy is a neurological disorder that affects the brain's ability to regulate sleep.

Another key difference between the two disorders is the presence of other symptoms. While hypersomnia is primarily characterized by excessive sleepiness, narcolepsy is often accompanied by other symptoms, such as sleep paralysis, hallucinations, and cataplexy. These symptoms can be debilitating and can greatly affect a person's quality of life.

Diagnosing hypersomnia and narcolepsy can be challenging, as the symptoms of these disorders can be similar. A thorough evaluation by a sleep specialist is necessary to determine the underlying cause of excessive sleepiness. This may involve a sleep study, in which the person spends the night in a sleep lab while their sleep is monitored.

Treatment for hypersomnia and narcolepsy also differs. Hypersomnia may be treated by improving sleep hygiene, addressing any underlying medical conditions, and making lifestyle changes such as increasing physical activity and avoiding alcohol or drugs. Narcolepsy is typically treated with medications that help regulate sleep, such as stimulants to keep the person awake during the day and medications to help them sleep at night. In addition, lifestyle changes such as napping at regular intervals and avoiding triggers such as stress and fatigue can help manage symptoms.

The following table highlights the major differences between Hypersomnia and Narcolepsy −





Hypersomnia is a pathological condition characterized by unusual sleepiness.

Narcolepsy is a chronic neurological disease characterized by excessive and sudden daytime sleepiness.


The main reasons for hypersomnia are prolonged and regular lack of sleep, physical or mental overload, emotional shocks, stress situations, medicines, skull trauma, tumors, intracerebral hematomas, infectious diseases, apnea, mental disorders, endocrine disorders.

The narcolepsy is with unknown etiology. Single inheritance cases are described, but there is often no occurrence in the family.


The main symptoms of hypersomnia are excessive nighttime sleep, sleepiness during the day, difficult wakening in the morning.

The main symptoms of narcolepsy are excessive daytime sleepiness and sudden sleep.

Other symptoms are temporary paralysis, hallucinations, muscle weakness, sleep disorders, disturbed night sleep.

Nocturnal sleep

Nocturnal sleep is prolonged in hypersomnia.

Nocturnal sleep is typically disrupted in narcolepsy.


The diagnostic methods of hypersomnia are Stanford sleepiness scale, sleep latency test, electro-polygraphy, polysomnography, clinical evaluation of the somatic, mental and neurological status of the patient, NMR of the brain, and in rare cases – cerebrospinal fluid examination.

The diagnosis of narcolepsy is based on the characteristic clinical picture, questionnaires, and polysomnography.


In conclusion, hypersomnia and narcolepsy are two sleep disorders that share some similarities but are distinct in their causes, symptoms, and treatment. Hypersomnia is characterized by excessive sleepiness throughout the day and can be caused by a variety of factors, while narcolepsy is a neurological disorder that causes sudden, uncontrollable episodes of sleepiness.

While both disorders can greatly impact a person's quality of life, a proper diagnosis and treatment plan can help manage symptoms and improve overall health and well-being.

Updated on: 02-Jun-2023


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