People with narcolepsy fall asleep repeatedly throughout the day, all unwittingly and even when engaged in engaging activities (eg during a conversation).
In addition to excessive daytime sleepiness and sleep attacks, narcolepsy is also noted for other symptoms, such as: cataplexy, hypnagogic hallucinations, sleep paralysis, automatic behavior and insomnia.
The diagnosis of narcolepsy is not immediate: in fact, it is necessary to consult a specialist in sleep disorders.
Currently, the treatment of narcolepsy is based only on symptomatic remedies and countermeasures, as there is still no specific cure that allows healing.
Sleep and Sleep Phases: A Brief Review
Sleep is characterized by two main phases, which alternate with each other for several times (4-5 cycles) during the night; these stages are:
- The NON-REM phase, or orthodox sleep, e
- The REM phase, or paradoxical sleep.
Each cycle consisting of a NON-REM phase and a REM phase typically lasts 90-100 minutes.
Only the correct alternation between the NON-REM phase and the REM phase guarantees a restful rest.
NON-REM phase
The NON-REM (or NREM) phase is characterized by four stages, during which sleep becomes progressively deeper.
The first two stages are, respectively, falling asleep and light sleep; at the third stage, the phase of deep sleep begins, which reaches its climax at the fourth stage.
It is in the fourth stage of the NREM phase that the human organism regenerates itself.
The NON-REM phase is shortened with each cycle: initially, it occupies a large part of the "NREM phase-REM phase" cycle (at least for two cycles); after that, it leaves more and more room for the REM phase.
REM phase
The REM phase is an active and agitated moment of sleep, so to speak; during its development, in fact, the individual dreams and moves his eyes rapidly (hence the acronym REM which means Rapid Eye Movement, i.e. rapid eye movement).
The REM phase initially covers a small portion of the nighttime sleep cycles; towards the morning, however, it lengthens, taking time away from the NREM phase.
, as, as will be seen better later, it seems to be related to an imbalance of some neurotransmitters involved in the regulation of sleep phases.Epidemiology: How Common is Narcolepsy?
Narcolepsy is an uncommon disorder: according to some statistics, in fact, 3-5 individuals per 10,000 people would be affected.
Narcolepsy affects men and women equally; this means, therefore, that it is not related to gender.
The diagnosis of narcolepsy generally occurs in adulthood (around the age of 25-40), although the disorder begins to manifest as early as adolescence or even earlier.
The reasons for a late diagnosis are to be found in the fact that, often, aspects such as sleepiness and fatigue in the young narcoleptic are mistakenly mistaken for listlessness, laziness and bad habits.
The still unclear aspects of the causes of narcolepsy are at least two: what induces the reduction of hypocretin levels in patients with this particularity and what is the causal factor of narcolepsy in subjects with normal hypocretin levels.
What is a Neurotransmitter?
A neurotransmitter is an endogenous chemical messenger used by neurons in the nervous system to communicate with each other and regulate a biological process or to impart a stimulus to muscles or glands.
Narcolepsy: What is Hypocretin and How Does it Work?
Secreted by the neurons of the hypothalamus, hypocretin is a neurotransmitter of a protein nature, which appears to be involved in the regulation of sleep phases.
In healthy subjects, the right levels of hypocretin would help ensure the correct alternation between the NON-REM phase and the REM phase of sleep.
In narcoleptic subjects, on the other hand, the reduction of hypocretin would lead to an "alteration of the cycle" NREM phase - REM phase, with the REM phase occurring without respecting the completion of the NREM phase or without the NREM phase ever starting.
Narcolepsy: What Alters Hypocretin Levels?
According to reliable studies, to affect the production of hypocretin and, subsequently, to cause narcolepsy would be an abnormal autoimmune reaction, from which derive antibodies that attack trib 2, a protein highly present in the brain area that is responsible for secreting the "hypocretin (probably, trib 2 is also involved in the production of the same hypocretin).
What triggers the abnormal Autoimmune Reaction?
The most important doubts regarding the onset of narcolepsy mainly concern the factors responsible for the abnormal autoimmune reaction.
According to experts, they could play a role:
- Some viral or bacterial infections;
- Achieving high levels of stress;
- A certain genetic / family predisposition;
- A sudden change in your sleep pattern
- The use of the Pandemrix vaccine against swine flu.
The doubts relating to the mechanism of onset of narcolepsy are basically due to the fact that the discoveries on hypocretin are recent: in fact, they date back to 2009-2010.
The possibility that the Pandemrix vaccine favors the onset of narcolepsy is still a subject of debate today.
Therefore, further studies are needed to actually understand if there is a real risk and what its extent is.
Narcolepsy in subjects with normal levels of hypocretin
Research has shown that a small portion of people with narcolepsy have normal levels of hypocretin.
These evidences, of course, have led experts to consider that other factors, other than hypocretin, may also contribute to the onset of narcolepsy.
At present, the precise causes of narcolepsy in patients with normal hypocretin levels are unknown.
Narcolepsy and Familiarity
Individuals with a family history of narcolepsy have a somewhat significant risk of developing the disorder.
However, it should be noted that only 1% of narcolepsy cases are family-related.
Familiarity with narcolepsy has led researchers to think that the onset of the condition in question is also linked to genetic factors.
daytime (daytime hypersomnia) and sudden sleep attacks;The first four manifestations of narcolepsy reported above are the most characteristic of the disorder; not surprisingly, they constitute what experts call the "tetrad of narcolepsy".
However, it should be noted that the only symptom always present in narcolepsy patients is excessive daytime sleepiness associated with sleep attacks; other disorders may never occur or appear only at some point in life.
To this it is worth adding that only a minority of narcoleptic patients (about 20%) show the entire symptomatology.
Excessive Sleepiness and Sudden Sleep Attacks
Excessive daytime sleepiness (or daytime hypersomnia) and sudden sleep attacks are persistent symptoms that plague the narcoleptic patient for life.
Their presence involves repeated daily naps, the duration of which can vary from a few minutes to a few hours.
The classic fit of drowsiness due to a boring situation or a period of physical stress is normal and should not be confused with narcolepsy.
The suspicion of narcolepsy must arise, however, when drowsiness and sleep attacks last for more than three consecutive months and also arise in active and unusual moments: for example, during a "work activity or while one is eating or talking."
In the narcoleptic, drowsiness occurs suddenly and unexpectedly every 90-120 minutes (this timing is variable, however) and, after the nap, the patient feels rested; however, this feeling of rest is transient and within a short time the patient is again seized by drowsiness and falls asleep again.
Cataplexy
Cataplexy is the sudden loss of control of the muscles in the body.
Those who suffer from it (about 7 out of 10 narcoleptic patients) feel a sudden lack of strength, while remaining conscious.
Typical manifestations of cataplexy are:
- Head swing;
- Sagging of the legs
- Confused speech;
- Blurred vision;
- Difficulty concentrating
- Sagging of the jaw
- Falling objects from the hands.
Often, the expressions of cataplexy are preceded by strong emotions, such as anger, euphoria, surprise or fear; this has led experts to believe that there may be a link between the patient's emotional state and the "attacks" of cataplexy.
The duration of the events varies from a few seconds to a few minutes; in the same way, the number of episodes per day is also variable.
Sometimes, due to their similarity, the "attacks" of cataplexy are confused with epileptic phenomena; however, these are two different pathological circumstances.
For further information: Cataplexy: Causes, Symptoms and TherapyHypnagogic hallucinations
Hallucinations are visions and perceptions of unreal things and sounds; they are extremely intense dreams.
In the narcolepsy patient, they occur above all in the passage from wakefulness to sleep, that is in the so-called hypnagogic period (this is why we speak of hypnagogic hallucinations); however, it should be noted that a minority of patients also suffer from hypnopompic hallucinations, ie shortly before awakening (hypnopompic period).
For further information: Hallucinations in Sleep: Causes and SymptomsSleep Paralysis
Sleep paralysis usually occurs upon awakening, but also shortly before falling asleep.
The patient, when he is conscious, feels that he is unable to move his body; in other words, he is unable to move his muscles, speak or open his eyes.
Lasting a few minutes, sleep paralysis episodes are a strange sensation, but they are not the sign of a serious associated neurological problem.
The presence of sleep paralysis is an important diagnostic finding.
For further information: Sleep Paralysis: Causes, Symptoms and TherapyAutomatic Behavior
We talk about automatic behavior when an individual continues an "activity (eg driving a vehicle) without then remembering that he has done it.
Some patients with narcolepsy become protagonists of episodes of automatic behavior during moments of daytime sleepiness.
These situations deserve considerable attention, because they could prove to be very dangerous: think for example of what could happen when a narcoleptic individual intent on an "injury-risk activity is seized at the same time by an attack of drowsiness and automatic behavior.
Disturbed Night Sleep
Disturbed night sleep is a very common disorder among narcoleptics and manifests itself as insomnia.
It seems that it is caused by a deficit of hypocretin and the effects that this deficit has on the phase shift between NON-REM and REM sleep.
It should be noted that, due to disturbed nocturnal sleep, the narcoleptic patient sleeps the same number of hours as a normal individual, although he falls asleep several times during the day.
Narcolepsy: the Complications
Narcolepsy can have important repercussions at school or work level, as the patient, in the eyes of not knowing his condition, turns out to be a lazy person with an unregulated lifestyle.
Furthermore, the presence of narcolepsy complicates interpersonal relationships and exposes you to dangers when you are doing work at risk of injury or activities that require concentration (eg driving).
Finally, some studies have shown that the problem of obesity is quite widespread among narcoleptics.
, the multiple sleep latency test and the Epworth sleepiness scale.It should be noted that, sometimes, the investigations listed above may not be sufficient to establish a definitive diagnosis; in such circumstances, lumbar puncture and nuclear magnetic resonance of the brain are used.
The diagnosis of narcolepsy is based on the evaluation of symptoms, on the observation of the patient's sleep pattern and on the exclusion, through appropriate investigations and tests, of all those conditions responsible for similar symptoms (differential diagnosis).
Narcolepsy: Anamnesis and Physical Examination
Medical history and physical examination are two preliminary investigations.
They can also be led by a doctor with no particular specialization in sleep disorders.
The physical examination consists of the collection of symptoms and the direct evaluation of the patient's health conditions.
The medical history, on the other hand, includes a series of questions relating to clinical history, family history and any pharmacological therapies in progress.
Medical history and physical examination provide useful information to narrow down the potential causes of daytime hypersomnia. For example:
- Investigating any pharmacological therapy in progress allows us to establish whether or not daytime sleepiness is due to the intake of a certain active ingredient;
- Evaluating the patient's health conditions, especially the oral cavity and nasal cavities, allows clarifying whether or not daytime sleepiness is due to a condition known as obstructive sleep apnea.
- Analyzing family history helps to know if daytime hypersomnia is a recurring disorder in the patient's family (remember that for some cases of narcolepsy a certain family predisposition affects).
Specific Tests for the Diagnosis of Narcolepsy
Polysomnography, multiple sleep latency test and Epworth sleepiness scale are three specific tests, the performance of which and interpretation of the results must be under the supervision of a sleep disorder specialist.
Polysomnography
Polysomnography consists of recording the brain, muscle, ocular, respiratory and cardiac activity of an individual while he is sleeping.
In order to perform this examination, the patient must sleep in a special room, equipped with the necessary equipment for monitoring the aforementioned functions (electroencephalogram for brain activity; electromyogram for muscle activity; electrooculogram for ocular activity; pulse oximeter for "respiratory activity; electrocardiogram for cardiac activity).
Thanks to the various parameters analyzed, polysomnography allows to interpret the alternation between the NON-REM phase and the REM phase.
For further information: Polysomnography: What is it for?Multiple Sleep Latency Test
The multiple sleep latency test is a measure of the time it takes the patient to fall asleep.
These tests classically follows the polysomnography (generally, it is performed the following day) and includes at least 4-5 measurements (of 35 minutes l "one about every 2 hours), in order to have a reliable result.
Subjected to multiple sleep latency tests, narcoleptic patients are shown to fall asleep very quickly and quickly enter REM sleep.
The multiple sleep latency test is considered positive for narcolepsy if the time to fall asleep is less than 8 minutes and if in at least two measurements the patient entered REM sleep early.
Epworth Scale of Somnolence
The Epworth scale is a measure of the level of daytime sleepiness.
This is a questionnaire that evaluates the probability of falling asleep in certain situations: for example while you are talking to another person, while you are in the car in the passenger seat, while you are reading, while sitting and inactive in a public place etc.
The answers to the various questions are worth a certain score.
If at the end of the questionnaire the points scored exceed a certain threshold, then it is legitimate to speak of narcolepsy; otherwise, narcolepsy is ruled out.
Narcolepsy and lumbar puncture: when is it needed?
Lumbar puncture involves the sampling of a portion of spinal cephalorachidian fluid and its subsequent laboratory analysis.
In narcoleptic patients, this test is the method that allows us to quantify hypocretin, the neurotransmitter that seems to be involved in most cases of narcolepsy.
Since it is a mildly invasive procedure, lumbar puncture is indicated only when doubts persist about the diagnosis of narcolepsy.
8 hours.
In addition, they indicate to schedule a few daily naps, lasting 15-20 minutes, to contain daytime sleepiness and feel rested at critical times of the day.
Drugs for Narcolepsy Somnolence
There are several drugs useful to control daytime narcolepsy hypersomnia, these are central nervous system stimulants, such as modafinil (the main one), armodafinil, methylphenidate, dexamphetamine, sunosis or pitolisant.
Able to reduce the number and severity of daytime sleep attacks, these drugs have several side effects; therefore, their intake must take place on the recommendation and strict supervision of the attending physician.
Drugs for Cataplexy, Hallucinations and Sleep Paralysis
Other drugs that can be used in the presence of narcolepsy are:
- Selective serotonin reuptake inhibitors (SSRIs) and serotonin and norepinephrine reuptake inhibitors (SNRIs).
Doctors prescribe these medicines with the intent of relieving cataplexy, hypnagogic hallucinations and sleep paralysis.
Some examples: fluoxetine and venlafaxine. - Tricyclic antidepressants. They may find use to control cataplexy.
Some examples: imipramine, protriptyline and clomipramine. - Sodium oxybate. It is a medicine that can relieve the symptoms of cataplexy; in some cases, moreover, it has also proved effective against daytime sleepiness.
All the drugs listed above have different side effects and some precautions for use; for example, while taking sodium oxybate you should not drink alcohol, as the interaction of these substances could cause severe breathing difficulties.
For further information: All Drugs for Narcolepsy ControlOther Countermeasures to Narcolepsy
To promote nighttime rest and limit daytime sleepiness, experts advise narcoleptic patients to:
- Regularly engage in physical activity, but avoid doing it in the evening (at least 5 hours before the time when you usually go to bed to sleep);
- Avoid heavy meals, especially in the evening;
- Avoid drinking alcohol and smoking;
- Set up a comfortable bedroom (eg: neither too hot nor too cold), "protected" from noise pollution and free from distractions (eg no television);
- To resort, just before going to bed, to activities that promote relaxation, such as a hot bath.
It should also be noted the "social importance of openly communicating the presence of a condition such as narcolepsy: keeping this disorder hidden, in fact, creates problems in interpersonal relationships, in the school environment (when the patient is still young) and in the workplace (when the patient is an adult); vice versa, informing friends, loved ones, teachers and employer avoids misunderstandings and helps to live better with the disorder.
