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Knowledge Base » Mental Health » Hypersomnia


The prevalence of hypersomnia is thought to be around 1 in 25,000, though the true prevalence and patient numbers are unknown. It is considered to be a rare disease. A rare disease is one where less than 1 in 2,500 people in the UK or 3 in 10,000 in Europe have it.

Hypersomnia is a kind of sleep disorder. Sleep disorders, or sleep-wake disorders, involve problems with the quality, timing and amount of sleep people get, which can result in daytime distress and impairment in functioning. Sleep-wake disorders often occur with medical conditions or other mental health conditions, such as depression, anxiety or cognitive disorders.

Examples of some common sleep disorders include:

Understanding Hypersomnia

Hypersomnia is a condition characterised by excessive sleepiness. This can manifest as prolonged night-time sleep, difficulty waking up in the morning, or excessive daytime sleepiness, where the person feels a persistent need to sleep even during the day despite getting an adequate or even excessive amount of night-time sleep. People with hypersomnia may also experience sleep inertia, which is a state of grogginess and disorientation upon waking.

There are several potential causes of hypersomnia, including:

  • Primary hypersomnia (idiopathic hypersomnia) – this is when excessive sleepiness is not attributed to any other medical condition. It is a neurological disorder where the brain has trouble regulating sleep-wake cycles.
  • Secondary hypersomnia – this occurs due to other underlying conditions such as other sleep disorders.
  • Medical conditions, for example a head injury, Parkinson’s disease or multiple sclerosis.
  • Mental health disorders, for example depression.
  • Use of certain medications or substances, for example sedatives or alcohol.
  • Poor-quality sleep or sleep deprivation.
  • Circadian rhythm disorders.

Hypersomnia differs from other sleep disorders in several key ways, as the primary characteristic of the disorder is excessive daytime sleepiness, regardless of how much sleep the individual gets at night. People with hypersomnia often sleep for long periods but still do not feel rested and they may have trouble waking up from naps or from a night’s sleep.

Comparisons to other sleep disorders include:

  • Insomnia – the primary symptom of insomnia is difficulty falling asleep or staying asleep. This leads to fatigue and impaired concentration due to insufficient or poor-quality sleep, but not necessarily excessive sleepiness.
  • Narcolepsy – the primary symptom of narcolepsy is sudden and uncontrollable episodes of sleep during the day, often accompanied by cataplexy which is sudden muscle weakness. Daytime sleepiness is often extreme and often sudden, with episodes of falling asleep abruptly during normal activities.
  • Sleep apnoea – the primary symptom is repeated interruptions in breathing during sleep, leading to poor sleep quality. This can lead to excessive daytime sleepiness due to frequent awakenings and disrupted sleep cycles at night, but is often associated with symptoms like loud snoring and choking.
  • Restless legs syndrome – the primary symptom is uncomfortable sensations in the legs and an irresistible urge to move them, typically worsening in the evening. This can lead to difficulty falling asleep or staying asleep, leading to daytime fatigue and tiredness, but not necessarily excessive sleep duration.
  • Circadian rhythm sleep disorders – the primary symptom is misalignment between the person’s sleep-wake cycle and the external environment, for example due to shift work or frequent jet lag. This can lead to daytime sleepiness or insomnia depending on the timing of the individual’s circadian rhythm versus their required schedule.

Types of Hypersomnia

There are several types of hypersomnia, which can be broadly categorised into primary and secondary hypersomnia. The main types are:

Primary Hypersomnia

  • Narcolepsy – Narcolepsy Type 1 (NT1) – this type includes excessive daytime sleepiness, cataplexy which is a sudden loss of muscle tone triggered by strong emotions, sleep paralysis, and hypnagogic/hypnopompic hallucinations.
  • Narcolepsy Type 2 (NT2) – this is similar to NT1 but without cataplexy. Patients still experience excessive daytime sleepiness and may have disrupted night-time sleep.
  • Idiopathic hypersomnia (IH) – this is characterised by chronic excessive daytime sleepiness despite sufficient or more than adequate night-time sleep. Unlike narcolepsy, there are no episodes of cataplexy, sleep paralysis, or hypnagogic hallucinations.

Secondary hypersomnia is caused by other medical conditions or external factors, for example sleep apnoea, obstructive sleep apnoea (OSA) and central sleep apnoea (CSA), and conditions such as Parkinson’s disease, multiple sclerosis, hypothyroidism, and head trauma can cause hypersomnia as a symptom. Some mental health disorders such as depression and other psychiatric disorders can lead to excessive sleepiness or prolonged sleep.

Recurrent hypersomnia includes conditions where hypersomnia occurs intermittently. People with this condition experience prolonged periods of sleep, often sleeping up to 18-20 hours a day during an episode, which can last for days, weeks, or even longer. These episodes are interspersed with periods of normal sleep and wakefulness, during which the person appears to function normally.

There are two primary types of recurrent hypersomnia:

  • Kleine-Levin Syndrome (KLS) – this is the most well-known form of recurrent hypersomnia. KLS typically begins in adolescence and is more common in males. In addition to excessive sleepiness, people with KLS may exhibit behavioural changes, such as irritability, confusion and excessive eating.
  • Menstrual-Related Hypersomnia – this type is characterised by recurrent episodes of excessive sleepiness that occur in relation to the menstrual cycle. It is less common and primarily affects women.

Symptoms of Hypersomnia

The symptoms of hypersomnia can significantly impact daily functioning and quality of life, necessitating medical intervention to identify underlying causes and appropriate treatment. Some of the key symptoms include:

  • Excessive daytime sleepiness – this is a persistent and overwhelming need to sleep during the day, often at inappropriate times such as during work or social activities.
  • Prolonged night-time sleep – this usually involves sleeping more than 10 hours per night regularly.
  • Difficulty waking up – finding it difficult to get out of bed in the morning, and often feeling groggy and disoriented upon waking.
  • Excessive napping – frequent, long naps that are not refreshing.
  • Cognitive impairment – including difficulty concentrating, memory problems and reduced attention span.
  • Decreased energy levels – persistent tiredness and low energy, even after adequate or extended periods of sleep.
  • Irritability or anxiety – mood changes, such as increased irritability or anxiety, possibly linked to chronic tiredness.
  • Impaired performance – including reduced performance at work, school, or in social situations due to sleepiness.

Causes and Risk Factors

The causes and risk factors of hypersomnia can be broadly categorised into primary hypersomnia, such as idiopathic hypersomnia, and secondary hypersomnia, which results from other medical conditions or lifestyle factors.

Some of the common causes include:

  • Sleep Apnoea – obstructive sleep apnoea (OSA) and central sleep apnoea (CSA) can lead to excessive daytime sleepiness due to repeated interruptions in sleep.
  • Narcolepsy – a neurological disorder that affects the brain’s ability to regulate sleep-wake cycles, leading to sudden sleep attacks and excessive daytime sleepiness.
  • Restless Legs Syndrome (RLS) – an uncomfortable urge to move the legs during periods of inactivity, often disrupting sleep.

Medical conditions:

  • Conditions such as Parkinson’s disease, multiple sclerosis, hypothyroidism and head trauma can cause hypersomnia as a symptom.
  • Mental health disorders – depression and other psychiatric disorders can lead to excessive sleepiness or prolonged sleep.
  • Chronic Fatigue Syndrome (CFS) – this is a condition characterised by extreme fatigue that does not improve with rest and can be associated with hypersomnia.
  • Hypothyroidism – an underactive thyroid gland can cause fatigue and excessive sleepiness.
  • Diabetes – poorly managed diabetes can lead to fatigue and increased sleepiness.
  • Medications – certain medications, such as sedatives, antidepressants and antihistamines, can induce hypersomnia as a side effect.
  • Substance abuse – use of alcohol, drugs or withdrawal from stimulants can cause excessive sleepiness.

Lifestyle factors:

  • An irregular sleep schedule – irregular sleep patterns or lack of a consistent sleep schedule can disrupt the body’s circadian rhythm, leading to hypersomnia.
  • Poor sleep hygiene – habits such as using electronic devices before bed, consuming caffeine late in the day, and not having a comfortable sleep environment can contribute to poor sleep quality and hypersomnia.
  • Genetic factors – there may be a genetic predisposition to hypersomnia, as it can sometimes run in families.

Other risk factors include:

  • Age – adolescents and young adults are more prone to hypersomnia due to changes in their sleep patterns and increased sleep needs.
  • Gender – some studies suggest that men may be more likely to develop hypersomnia, especially when related to sleep apnoea.
  • Shift work – people who work night shifts or have irregular work hours are at higher risk of developing hypersomnia.
  • Sedentary lifestyle – lack of physical activity can contribute to poor sleep quality and hypersomnia.
  • Obesity – being overweight can increase the risk of conditions like sleep apnoea, which in turn can cause hypersomnia.

Circadian rhythm disorders:

These disorders involve a misalignment between an individual’s internal circadian clock and the external environment, leading to hypersomnia.

  • Delayed Sleep-Wake Phase Disorder (DSWPD) – a significant delay in the timing of sleep, leading to difficulty waking up in the morning and excessive sleepiness during the day.
  • Advanced Sleep-Wake Phase Disorder (ASWPD) – an early sleep onset and wake time, often leading to difficulty staying awake in the evening and waking up very early.
  • Kleine-Levin Syndrome (KLS) – also known as ‘Sleeping Beauty Syndrome’, KLS is a rare disorder characterised by recurrent episodes of excessive sleep, along with cognitive and behavioural changes such as excessive eating, hypersexuality and confusion during episodes.

Diagnosis and Evaluation

Accurate diagnosis of hypersomnia requires a thorough assessment combining clinical evaluations, patient history and objective testing. Collaboration with a sleep specialist is often essential in order to identify the specific type of hypersomnia and tailor appropriate treatment strategies.

Diagnosing and evaluating hypersomnia will usually involve clinical assessments, taking patient history, and various diagnostic tests. The process will usually involve:

  • A clinical assessment – taking the patient’s history including a detailed sleep history, including bedtime, wake time, sleep duration and nocturnal awakenings; daytime sleepiness in frequency, duration and the impact on daily activities; and general sleep habits including naps, sleep environment and sleep hygiene.
  • Medical history – in order to look at comorbid conditions, for example depression, anxiety, hypothyroidism, medications and substance use.
  • Family history – including any sleep disorders, especially narcolepsy or other hypersomnia disorders.
  • Symptoms evaluation – this involves looking at the primary symptoms, for example excessive daytime sleepiness, unrefreshing naps, difficulty waking up and associated symptoms, for example cognitive impairment, and mood changes.
  • A physical examination – this will include a general physical examination to rule out underlying medical conditions and a neurological examination if any neurological disorders are suspected.
  • Sleep diary and questionnaires – this will usually involve a 1-2 week record of sleep patterns, daytime sleepiness, naps, and other relevant activities as well as sleep questionnaires.
  • Polysomnography (PSG) – this is an overnight sleep study to monitor and record physiological data during sleep. It assesses sleep stages, sleep architecture, breathing patterns, oxygen levels and limb movements. It also rules out other sleep disorders such as sleep apnoea or periodic limb movement disorder.
  • Multiple Sleep Latency Test (MSLT) – this should be conducted the day after a PSG and consists of five nap opportunities scheduled two hours apart throughout the day. It measures how quickly the patient falls asleep and the occurrence of REM sleep during naps. This helps to differentiate between narcolepsy and other hypersomnia disorders.
  • Maintenance of Wakefulness Test (MWT) – this assesses the ability to stay awake in a conducive sleep environment. It is useful for evaluating the severity of sleepiness and the effectiveness of treatment.
  • Actigraphy – this is a wearable device that tracks sleep-wake patterns over several days or weeks. It provides objective data on sleep duration, timing and variability.
  • Laboratory tests – blood tests to rule out metabolic or endocrine disorders.
  • Imaging and other tests – brain imaging (MRI or CT) if structural abnormalities or neurological conditions are suspected.

Coping with Hypersomnia

Coping with hypersomnia involves a combination of medical treatment, lifestyle changes and coping strategies in order to manage excessive daytime sleepiness and improve overall quality of life.

It’s crucial to get a proper diagnosis from a doctor, as hypersomnia can be a symptom of various underlying conditions like sleep apnoea, depression or narcolepsy. Also follow prescribed treatments, which might include medications like stimulants, antidepressants or wakefulness-promoting agents.

Undergoing a sleep study or multiple sleep latency test (MSLT) can help diagnose the specific type of hypersomnia and guide treatment.

Some lifestyle changes that may help include:

  • Maintaining a regular sleep schedule – try to go to bed and wake up at the same time every day, even on weekends, to regulate your internal clock.
  • Create a restful sleep environment – ensure your bedroom is dark, quiet and cool. Use comfortable bedding and limit distractions like electronic devices.
  • Healthy diet and exercise – eat a balanced diet rich in fruits, vegetables and lean proteins. Avoid heavy meals and caffeine close to bedtime. Regular physical activity can help improve sleep quality, but you should avoid vigorous exercise too close to bedtime.

Some coping strategies include:

  • Short naps – you could try to schedule short, strategic naps during the day to help reduce sleepiness without disrupting night-time sleep.
  • Stress management – practise relaxation techniques such as meditation, deep breathing exercises or yoga to reduce stress and improve sleep quality.
  • Support from friends and family members – communicate with family, friends and employers about your condition to gain their support and understanding.
  • Consider joining a support group for people with sleep disorders to share experiences and coping strategies.
  • Avoid alcohol and drugs – these can exacerbate sleep problems and should be avoided, especially close to bedtime.
  • Limit screen time – reduce your exposure to screens before bedtime as the blue light can interfere with your sleep cycle.
  • Keep a sleep diary – track your sleep patterns, daytime sleepiness and any factors that affect your sleep in order to identify patterns and triggers.
  • Regular check-ups – regularly check in with your healthcare provider to adjust treatments as needed and address any new symptoms or concerns.
  • Cognitive behavioural therapy (CBT) and CBT for insomnia (CBT-I) – this therapy helps change thoughts and behaviours around sleep, which can be effective even for hypersomnia by improving overall sleep quality and habits.
  • Work and school adjustments – discuss flexible work or school hours or the possibility of working from home to accommodate your need for rest.
  • Task management – prioritise tasks and take regular breaks in order to manage fatigue throughout the day.

Medical Treatment and Management

Medical treatments for hypersomnia are usually focused on treating the underlying cause and aim to improve alertness and quality of life.

Some common approaches include:

  • Medications – stimulants are often prescribed in order to promote wakefulness.
  • Antidepressants – certain antidepressants, especially those with stimulant effects like selective serotonin and norepinephrine reuptake inhibitors (SNRIs), can help manage symptoms.
  • Sodium oxybate – this medication is particularly effective for patients with narcolepsy, a condition often associated with hypersomnia. It helps improve night-time sleep, which can reduce daytime sleepiness.

If hypersomnia is secondary to another condition, such as sleep apnoea, depression or hypothyroidism, treating the primary condition is crucial. For instance, continuous positive airway pressure (CPAP) therapy for sleep apnoea can alleviate symptoms of hypersomnia.

Cognitive behavioural therapy (CBT) – particularly CBT for insomnia (CBT-I), can help address maladaptive sleep behaviours and thoughts, promoting better sleep patterns.

Light therapy – exposure to bright light during the morning can help regulate the sleep-wake cycle, particularly for individuals whose hypersomnia is related to circadian rhythm disorders.

Undergoing a polysomnogram or multiple sleep latency test (MSLT) can help diagnose the specific type of hypersomnia and guide treatment.

The Sleep Charity aims to provide access to high-quality information and advice to deal with most sleep issues. They also campaign for improvements to the support available as well as providing accredited training for professionals so they can offer sleep support to the people they work with.

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About the author

Claire Vain

Claire Vain

Claire graduated with a degree in Social Work in 2010. She is currently enjoying her career moving in a different direction, working as a professional writer and editor. Outside of work Claire loves to travel, spend time with her family and two dogs and she practices yoga at every opportunity!

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