Hypersomnia: omnipresent sleep for a "hyperpathology"!

Hypersomnia, or when sleep becomes tiring, abusing your time and your health. This maxim could have been taken from a fable by La Fontaine, but unfortunately it is the relentless reality faced when hypersomnia shows its face.

A relatively little-known pathology in its origins when it takes the form of idiopathic hypersomnia, this "super" or "hyper" long-term fatigue navigates the lives of those who suffer from it without ever caring about the duration of its sleep cruise, nor the short stops of wakefulness. Uncertain, even unknown origin, do we really know the causes of hypersomnia?

Protean, this sleep disorder finds a home in several pathologies and many diagnoses. But then, what do we really know about hypersomnia? Here are some answers offered by Captain Sleep, commander of the ship Hypersomnia!

What is hypersomnia?

According to INSERM¹ (National Institute of Health and Medical Research), hypersomnia is defined as a neurological disorder characterized by a significant state of fatigue and an excessive need for sleep. It is also manifested by numerous daytime sleepiness episodes.

Two types of hypersomnias are distinguished :

1. Primary hypersomnia (or central hypersomnia): these are the rarest, and their causes are not always known. There are 3 forms:
• idiopathic hypersomnia
• narcoleptic hypersomnia
• recurrent hypersomnia or Kleine-Levin syndrome
2. Secondary hypersomnia: these are the most common, often the consequence of another phenomenon (fatigue, pathologies, trauma, psychological disorders, use of narcotic substances...)

As a general rule, a person is considered hypersomniac when they sleep more than 11 hours per day, which constitutes quite a substantial sleep cruise!

Hypersomnia in a few figures

Hypersomnia is a rare disease and, as such, it is difficult to quantify. However, the prevalence of hypersomnia is estimated between 4 and 6% of the population² in its most common form (secondary hypersomnias, for example psychiatric hypersomnia).

Primary hypersomnias are much rarer, notably idiopathic hypersomnia. The latter would affect 1 to 5 people per 10,000 (1-5/10,000)³ when accompanied by an extended sleep duration (up to 10 hours), which is, for example, 5 times less than the prevalence of narcolepsy. When it is not accompanied by extended sleep duration, it is even rarer, with a prevalence estimated at about 1 per 100,000⁴.

Idiopathic hypersomnia would occur between 20 and 30 years of age, affecting both men and women. However, there is very little data to further quantify hypersomnia.

What are the causes of hypersomnia?

Secondary hypersomnias

They concern the majority of us and, unlike primary hypersomnias, the causes of secondary hypersomnias are identifiable. They can affect anyone during their lifetime, especially when they result from a pathology or follow a sleep disorder. Here are the main secondary hypersomnias:

• significant sleep deficit, physical fatigue due to other sleep disorders (narcolepsy, sleep apnea, restless legs syndrome)
• psychiatric disorders: depression, dysthymia, bipolar disorder…
• neurological diseases (neurodegeneration, trauma)
• infectious diseases (Epstein-Barr virus, Guillain-Barré syndrome)
• substance use: abuse of hypnotic or sedative medications, sudden cessation of stimulants, toxic organic solvents…
• endocrine or metabolic diseases: diabetes, hypothyroidism, pancreatic or renal insufficiency…
• cancers

Primary hypersomnias

For this type of hypersomnia, the causes are not sufficiently known. Primary hypersomnia is not the consequence of a disease, psychiatric disorder, or behavior.

However, it is assumed that a malfunction of certain wakefulness systems could be involved. In the case of idiopathic hypersomnia, it seems that 20 to 30% of cases follow family history⁵.

As we can see here, central hypersomnias (or primary) remain quite mysterious regarding their origins, perhaps even more so than some other sleep disorders, giving this sleep journey an almost supernatural character! Indeed, there are phenomena that science and medicine cannot yet fully explain.

Symptoms of hypersomnia

The symptoms of hypersomnia are quite characteristic, even if they are found in other pathologies. Here are the main symptoms common to the different types of hypersomnias:

• intense fatigue, feeling of exhaustion: urgent desire to sleep, which can be temporary or constant depending on the type of hypersomnia
• excessive daytime sleepiness
• long sleep: prolonged sleep duration
• difficulties waking up: "sleep drunkenness" syndrome
• daytime hypovigilance

Idiopathic hypersomnia, on the other hand, has particular characteristics:

• excessive and constant daytime sleepiness
• normal or increased night sleep without abnormalities, but non-restorative
• very difficult awakening: inertia and/or sleep drunkenness
• long and non-restorative naps

In the case of recurrent hypersomnia/Kleine-Levin syndrome, the characteristics are as follows:

• recurrent episodes lasting several days
• cognitive-behavioral disorders
• 15 to 20 hours of sleep per day, for several days, even several weeks

Regarding narcolepsy, which is also considered a central hypersomnia, symptoms of excessive fatigue and prolonged sleep time may also appear, but it is mainly characterized by cataplexy (loss of muscle tone).

How can hypersomnia be diagnosed?

Hypersomnia is primarily diagnosed through an interview conducted by the doctor, as well as a clinical and psychological examination. A diagnosis of exclusion is then performed, meaning that other possible causes of hypersomnolence (chronic fatigue, overwork, phase shift, use of hypnotic drugs or sedative medications, withdrawal from stimulant drugs…) are sought to be eliminated.

Idiopathic hypersomnia is the most difficult to diagnose. Following this thorough interview, after ruling out other possible causes of sleepiness and chronic fatigue syndrome, it is necessary to recognize and characterize the excess sleep. The doctor can then direct the patient to various examinations:

• MRI and/or CT scan
• actimetry (wristband-type device to measure sleep and wake rhythms)
• sleep diary (to be filled out daily by the patient)
• polysomnography (complete analysis of a sleep recording performed in a laboratory, using electrodes)
• iterative daytime sleep latency tests

For certain secondary hypersomnias, additional tests (brain imaging, biology) may be necessary to characterize them.

Nowadays, one can quite simply "self-diagnose" regarding sleepiness by taking an online test⁶ on specialized sites or blogs. The answers to the questions easily determine problems of excessive daytime sleepiness thanks to the Epworth scale. Do not hesitate to climb this scale to learn more in case of fatigue or unusual sleepiness!

For all practical purposes, Captain Sleep, commander of the ship Hypersomnia, informs the wisest among us (not to say the oldest!) that excessive daytime sleepiness beginning to appear in elderly people should alert them (or their relatives). Indeed, a recent study⁷ highlights that these sleepiness episodes could be indicators of chronic diseases, with "a risk of diabetes or high blood pressure multiplied by 2.3" and "a risk of cancer multiplied by 2." It is therefore important to monitor the sleep of our venerable elders (sailors)!

What treatments for hypersomnia?

We do not know how to cure hypersomnia, there are only symptomatic treatments to reduce its effects on patients. The difficulty in diagnosing certain central hypersomnias (idiopathic hypersomnia) and the very delicate handling of the associated medications mean that the treatment of hypersomnia, as a rare disease, mainly goes through the «Centres de référence et de compétence Narcolepsies et Hypersomnies Rares ».

The treatment of symptoms is mainly drug-based:

• for daytime sleepiness: use of wakefulness stimulants (modafinil, methylphenidate, amphetamines)
• for Kleine-Levin syndrome: lithium, valproate, corticosteroids or treatment for behavioral disorders
• for narcoleptic hypersomnia: sodium oxybate, antidepressants, selective serotonin reuptake inhibitors, pitolisant

Of course, drug treatments carry risks of side effects. On the other hand, when the patient suffers from psychiatric hypersomnia, it is extremely difficult to treat because some antidepressants themselves cause sleep disorders!

Moreover, in the case of idiopathic hypersomnia, wakefulness stimulants have no positive effect on sleep inertia ("sleep drunkenness").

In any case, therapeutic education is essential. Knowing your disease, maintaining an appropriate lifestyle (limiting alcohol consumption, having regular physical activity…), establishing "sleep rituals" (fixed times for naps, bedtime, and waking) are daily habits that can help relieve the symptoms of hypersomnia.

However, progress in identifying the causes of this disease and the resulting therapeutic advances are eagerly awaited to make the experience of the sleep cruise a little (or even much) less burdensome! So be sure to fill out the "sleep" book before disembarking!

To illustrate the topic of hypersomnia, here is a video from the « Neuroscience Education Institute » that summarizes the ins and outs of this sleep disorder.

Sources:

[1] and [4] Hypersomnias and narcolepsy: when too much sleep is pathological, site of « l’INSERM », September 2017 [2] Hypersomnia, Y. Dauvilliers, A. Buguet, « Dialogues in Clinical Neuroscience », December 2005 [3] Idiopathic Hypersomnia, site « Orphanet », July 2020 [5] Idiopathic Hypersomnia, site « Fondation Sommeil », 2020 [6] Do you suffer from sleep disorders?, site « Fondation Sommeil », 2020 [7] Hypersomnolence is a Significant Predictor of New Medical Conditions Among Elderly People in a Longitudinal Study of the General Population, Maurice M. Ohayon, Shannon Sullivan et al, « Neurology », April 2020