What Is Hypersomnia

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Hypersomnia is the medical term for daytime sleepiness. Specifically, hypersomnia is excessive daytime sleepiness that can lead to its suffers falling asleep during the day, which severely impacts their daily activities and overall quality of life. It is a symptom of many different conditions, which vary in their causes, risk factors, and treatments. 

Causes of hypersomnia

Daytime sleepiness can be categorised as either primary hypersomnia or secondary hypersomnia. 

Primary hypersomnia 

This is when there are  no underlying reasons for causing excessive daytime sleepiness, and it is its own medical condition. There are four conditions that  are classified as primary hypersomnias 

  • Narcolepsy type 1- narcolepsy is the disorder of sudden abrupt sleep attacks. Type 1 has cataplexy- where intense emotions, such as laughing, trigger sudden muscle weakness, that can cause falls. 
  • Narcolepsy type 2- this does not have cataplexy and has less severe symptoms than type 1 
  • Kleine-Levin syndrome- or ‘sleeping beauty syndrome’ is a rare sleep disorder that is also characterised by mental and behavioural difficulties, alongside compulsive eating, and hypersexuality that appears in episodes lasting from a week to a few months.1 
  • Idiopathic hypersomnia- when the cause of hypersomnia is unknown 

Secondary hypersomnia

This is when daytime sleepiness is due to another known cause. 

  • Other sleep disorders- obstructive sleep apnoea, delayed sleep phase syndrome 
  • Mental health conditions- depression, bipolar disorder 
  • Neurological conditions- epilepsy, Parkinson’s, multiple sclerosis 
  • Endocrine disorders- hypothyroidism 
  • Medication- benzodiazepines, barbiturates, and sleep medicine
  • Alcohol and recreational drugs
  • Insufficient sleep syndrome- when there is no underlying condition, but inadequate sleep at night can lead to feeling sleepy during the day2,3

Signs and symptoms of hypersomnia

Excessive daytime sleepiness can be characterised by 

  • Sleeping during the day 
  • Difficulty waking up from sleep (sleep inertia)  
  • Problems with memory, or ‘brain fog’  
  • Sleep drunkenness- drowsy when waking up 
  • Slow speech 
  • Anxiety 
  • Irritation 
  • Decreased energy4

Often, people with hypersomnia suffer from daytime sleepiness despite achieving adequate sleep during the night. Idiopathic hypersomnia is characterised by prolonged nocturnal sleep of more than 10 hours, and sleep inertia.5 

Alongside the above symptoms, people with narcolepsy can experience additional symptoms, including

  • Hallucinations- when falling sleeping (hypnagogic hallucinations) or immediately after waking up (hypnopompic hallucinations) 
  • Sleep paralysis- the inability to move after waking up 
  • Cataplexy- can sometimes be triggered by anger or involve only part of the body, such as the jaw or face6

In secondary hypersomnia, other symptoms may help determine the underlying cause 

  • Loud snoring and breathing during the night- sleep apnoea 
  • Low mood, loss of interest in life- depression 
  • Mood swings ranging from extreme highs to extreme lows- Bipolar disorder
  • Weight gain, slowed heart rate, cold sensitivity, and constipation- hypothyroidism
  • Tremor- neurological condition6,7

Management and treatment for hypersomnia

The best approach to treating hypersomnia depends on its underlying cause, these include medications, therapies, and lifestyle modifications.

There are various drugs available that can boost alertness and reduce tiredness and the urge to fall asleep. 

  • Wakefulness drugs- such as Modafinil 
  • Psychostimulants- methylphenidate (Ritalin), or dextroamphetamine (Adder all) 

For cataplexy, medication includes 

  • Selective serotonin reuptake inhibitors (SSRIs)- typically used to treat depression, these medications also help reduce hallucinations and sleep paralysis 
  • Tricyclic antidepressants- these older medications are used less often due to their side effects, but they can be prescribed
  • Other options- sodium oxybate, flumazenil2

There is no curative treatment for Kleine-Levin syndrome. Since its symptoms fluctuate, management may change according to the needs of the patient. Options available are 

  • Therapy and emotional support can help manage the psychological challenges and come to terms with the condition. 
  • Medication can be used to help control the episodes. Carbamazepine, risperidone, dopamine agonists, and gabapentin are medications that can be prescribed during this time1

Sleep apnoea is a serious disorder characterised by breathing stopping and starting throughout the night, the most common form being obstructive sleep apnoea, which is caused by the muscles of the throat relaxing, blocking the air from reaching the lungs. It can be treated by

  • Lifestyle changes- losing weight, reducing alcohol, and stopping smoking can help improve symptoms 
  • CPAP machine - this device that is worn throughout the night gently pumps air into a mask you wear over your mouth and nose. This stops your airway from narrowing during your sleep, however, it can be nosy and uncomfortable. 
  • Surgery- to remove large tonsils if they are obstructing the airway8


How is hypersomnia diagnosed

A full medical history, including information on any preexisting medical conditions, including mental health, or any medication that you are on.

  • Questionnaires- The Epworth Sleepiness Scale are 8 questions ranked from 0-3 regarding their daytime sleepiness during certain activities, such as watching TV, or eating lunch. Generally, scores above 11 are considered to signify excessive daytime sleepiness9
  • Sleep diary- keeping track of your sleeping patterns and habits can help give your doctor more evidence to help your diagnosis. Typically, idiopathic hypersomnia requires at least three months of excessive sleepiness to be diagnosed
  • Polysommongrapy-  an overnight sleep study performed in a specialised centre can help monitor your brain activity, heart rhythms, and muscle movements during the different stages of sleep 
  • Multiple sleep latency test- a daytime sleep study, usually performed the morning after polysomnography, that measures how often you fall asleep during 20-minute nap trials that are two hours apart. Narcolepsy requires two incidences of reaching REM sleep during this test
  • Actigraphy- A device worn like a watch that detects when there is a movement to assess sleep-wake cycles 
  • Laboratory studies- taking blood samples for underlying diseases and the level of drugs and alcohol can help detect causes of secondary hypersomnia2,6,10

How can I prevent hypersomnia

Hypersomnia, unfortunately, cannot be prevented. However, maintaining good sleep hygiene can help reduce the burden of symptoms, and may improve the quality of life. 

Here are some methods to help maintain good sleep hygiene 

  • Maintain a regular sleep schedule 
  • Only sleep in your bed, avoid watching TV or looking at your phone 
  • Exercise daily, but not right before bedtime 
  • Keep your room dark and calm 
  • Avoid caffeine and smoking in the evening 
  • If you can’t sleep in bed, get up and try again later.
  • Avoid night shifts6

Who is  at risk of hypersomnia

Since hypersomnia can have many different causes, various different groups of people are  at risk of different disorders. Obstructive Sleep apnoea, a common cause of hypersomnia, risk factors include

  • Obesity- increased body fat means that fat can deposit around the upper airway 
  • Male- Men are two-three times more likely to suffer from sleep apnoea than women 
  • Age- the risk of obstructive sleep apnoea increases with age 
  • Family history 
  • Thicker neck or narrower airway 
  • Alcohol and smoking
  • Nasal congestion- from allergies 
  • Congestive heart failure 
  • Hypertension
  • Type 2 diabetes
  • Polycystic ovary syndrome11

How common is hypersomnia

Hypersomnia is reported to affect approximately 4-6% of the population. It is more common in men, as they are more likely to suffer from obstructive sleep apnoea, one of the main causes behind secondary hypersomnia. Narcolepsy is extremely rare and affects less than 0.03% of the population.3

When should I see a doctor

You should see a healthcare provider if you have noticed any problems in your sleep, such as falling asleep often during the day, having difficulty staying awake, and that sleepiness is affecting your life.7


Hypersomnia is the condition of excessive sleepiness during the day, often despite sleeping well during the night, to the extent that it interferes with daily life. If you or someone close to you are experiencing any symptoms described above, get in contact with your healthcare provider to help find the best way to manage your symptoms. 


  1. Shah F, Gupta V. Kleine–Levin syndrome (KLS). StatPearls [Internet]. 2022 Aug 8 [cited 2023 Feb 25]; Available from: https://www.statpearls.com/ArticleLibrary/viewarticle/131266
  2. Hypersomnia [Internet]. Cleveland Clinic. [cited 2023 Feb 25]. Available from: https://my.clevelandclinic.org/health/diseases/21591-hypersomnia
  3. Dauvilliers Y, Buguet A. Hypersomnia. Dialogues Clin Neurosci. 2005;7(4):347–56.
  4. Hypersomnia [Internet]. National Institute of Neurological Disorders and Stroke. [cited 2023 Feb 25]. Available from: https://www.ninds.nih.gov/health-information/disorders/hypersomnia
  5. Rassu AL, Evangelista E, Barateau L, Chenini S, Lopez R, Jaussent I, et al. Idiopathic Hypersomnia Severity Scale to better quantify symptoms severity and their consequences in idiopathic hypersomnia. J Clin Sleep Med. 2022 Feb 1;18(2):617–29.
  6. Karna B, Sankari A, Tatikonda G. Sleep Disorder. In: StatPearls [Internet]. StatPearls Publishing; 2022.
  7. Excessive daytime sleepiness (hypersomnia) [Internet]. nhs.uk. [cited 2023 Feb 25]. Available from: https://www.nhs.uk/conditions/excessive-daytime-sleepiness-hypersomnia/
  8. Sleep apnoea [Internet]. nhs.uk. [cited 2023 Feb 25]. Available from: https://www.nhs.uk/conditions/sleep-apnoea/
  9. About the ESS [Internet]. [cited 2023 Feb 25]. Available from: https://epworthsleepinessscale.com/about-the-ess/
  10. Idiopathic hypersomnia [Internet]. 2022 [cited 2023 Feb 25]. Available from: https://www.mayoclinic.org/diseases-conditions/hypersomnia/diagnosis-treatment/drc-20362338
  11. Sleep apnea [Internet]. Mayo Clinic. 2022 [cited 2023 Mar 9]. Available from: https://www.mayoclinic.org/diseases-conditions/sleep-apnea/symptoms-causes/syc-20377631

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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Lauren Young

Doctor of Medicine - MD, Medical University of Sofia, Bulgaria

Lauren is a newly qualified doctor, who recently returned to the UK to pursue a career as a GP. Her passions lie in public health, medical education and health advocacy. An avid reader, Lauren has found great joy in combining her love of medicine and the written word in writing health articles for Klarity.

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