Rem Sleep Excess: Narcolepsy's Signature

Narcolepsy is a sleep disorder characterised by excessive daytime sleepiness and abnormal REM sleep. People with narcolepsy tend to sleep the same number of hours per day as those without it, but the quality of sleep is often poor. The condition is associated with abnormal rapid eye movement (REM) sleep phenomena, including cataplexy, sleep paralysis, sleep-related hallucinations, REM sleep behaviour disorder, abnormal dreams, and fragmented REM sleep. Narcolepsy is typically diagnosed based on symptoms and sleep studies, and while there is no cure, it can be managed through behavioural strategies, lifestyle changes, social support, and medication. The exact cause of narcolepsy is unknown, but it is believed to be linked to several factors, including genetic, autoimmune, and environmental factors.

Narcolepsy type 1 is characterised by cataplexy and low CSF orexin levels

Narcolepsy is a chronic sleep disorder characterised by excessive daytime sleepiness (EDS) and abnormal manifestations of REM sleep, such as cataplexy, sleep paralysis and hypnagogic hallucinations. Narcolepsy type 1 (NT1) is distinguished by the presence of cataplexy and low levels of cerebrospinal fluid (CSF) orexin (also known as hypocretin).

Orexin is a neuropeptide produced by neurons in the lateral hypothalamus that plays a crucial role in maintaining wakefulness and regulating motor functions. A deficiency in orexin is strongly linked to NT1, with low CSF orexin levels considered a definitive diagnostic indicator. The pathophysiology of NT1 involves the loss of orexin-producing neurons, resulting in low CSF orexin levels of less than 110 pg/ml.

The diagnostic criteria for NT1 include EDS for at least three months, cataplexy, and CSF orexin levels below 110 pg/ml. Cataplexy is characterised by transient episodes of muscle weakness triggered by emotions, typically lasting less than two minutes. The presence of the HLA DQB1*0602 allele is also associated with NT1.

The distinction between NT1 and narcolepsy type 2 (NT2) is primarily based on the presence or absence of cataplexy and corresponding CSF orexin levels. NT2, also known as narcolepsy without cataplexy, is confirmed by sleep testing criteria, EDS symptoms, CSF orexin levels greater than 110 pg/ml, and the absence of cataplectic episodes.

While the MSLT is commonly used for diagnosis, it is not always reliable, and CSF orexin levels can provide additional diagnostic value, particularly when there is uncertainty. However, CSF orexin levels alone may not be sufficient for a definitive diagnosis, especially in cases of severe depression.

Narcolepsy type 2 does not involve cataplexy and CSF orexin levels are normal

Narcolepsy is a sleep disorder characterised by excessive daytime sleepiness. It is associated with abnormal rapid eye movement (REM) sleep phenomena. Narcolepsy is split into two types. Type 1 is characterised by the presence of cataplexy and orexin deficiency in the hypothalamus. Cataplexy is a specific symptom of narcolepsy, referring to transient episodes of muscle weakness triggered by emotions.

Narcolepsy type 2 does not involve cataplexy and is characterised by normal orexin levels in the cerebrospinal fluid (CSF). Orexin (also known as orexin-A or hypocretin-1) is a neuropeptide involved in the sleep/wake cycle in humans. It is produced in the hypothalamus.

Narcolepsy type 2 is considered a diagnosis of exclusion, as it is a complex and heterogeneous disorder. It is difficult to establish a clear diagnosis for these patients, as there is a possibility of false-positive Multiple Sleep Latency Tests (MSLTs). MSLT is a diagnostic tool for narcolepsy, with a mean sleep latency of less than or equal to 8 minutes and the observation of at least two sleep onset rapid eye movement periods (SOREMPs) during MSLT being established as diagnostic criteria for narcolepsy.

Narcolepsy type 2 is likely to have a different aetiology to type 1, as it is not associated with orexin deficiency. However, a post-mortem study of a single case of narcolepsy type 2 showed a partial loss of orexin cells in the posterior hypothalamus, accompanied by prominent gliosis. This suggests that orexin neurotransmission may be partially compromised in narcolepsy type 2.

Narcolepsy is a clinical syndrome of hypothalamic disorder, but the exact cause is unknown

Narcolepsy is a chronic neurological disorder that impairs the brain's ability to regulate sleep-wake cycles. It is characterised by excessive daytime sleepiness (EDS), even after a full night's sleep. People with narcolepsy tend to fall asleep suddenly during the day, and often describe this as "sleep attacks". The condition is caused by a disruption to the normal sleep cycle, with people frequently entering REM sleep much more quickly than usual, and experiencing elements of sleep and wakefulness at the same time.

Narcolepsy is a clinical syndrome of hypothalamic disorder. The hypothalamus is a specific area in the brain that helps to regulate sleep and wake times. In people with narcolepsy, the neurons in the hypothalamus that produce orexin (also known as hypocretin) either stop working or are destroyed. Orexin is a chemical molecule that helps to regulate sleep-wake cycles and acts as a neurotransmitter to enable nerve cells to communicate.

The exact cause of narcolepsy is unknown, but it is thought to be the result of several factors. About 90-95% of people with type 1 narcolepsy have a specific genetic mutation that affects their immune system. However, about 25% of people also have this mutation but do not have narcolepsy, so experts rarely test for it. There is also evidence that narcolepsy can run in families, with a high relative risk among first-degree relatives.

Another potential cause is an autoimmune problem, where the body's immune system attacks the neurons that make and use orexins, or the orexins themselves. In people with type 1 narcolepsy, the most common form of the condition, the loss of neurons that produce orexin is thought to be linked to abnormalities in the immune system. This can be triggered by certain infections, such as H1N1 influenza or strep throat.

While the causes of type 1 narcolepsy are better understood, the reasons behind type 2 narcolepsy are less clear. Experts suspect it happens for similar reasons, such as a less severe loss of the neurons that use orexin or a problem with how orexin travels in the brain.

In rare cases, narcolepsy can be caused by damage to the hypothalamus as a result of head injuries, strokes, brain tumours, or other conditions.

Narcolepsy can have a significant impact on daily activities, including work and social life. However, the condition usually responds well to treatment, and people with narcolepsy can manage the effects through medication and lifestyle changes.

Narcolepsy is treatable but not curable

Narcolepsy is a sleep disorder that causes an overwhelming urge to fall asleep during the day. While it is not curable, it is treatable, and those affected can manage the condition and adapt to its effects.

Narcolepsy is caused by the brain's inability to control sleep patterns. People with narcolepsy often fall asleep during the day, and experience symptoms such as sleep paralysis, hallucinations, and cataplexy, or sudden muscle weakness. The condition can be dangerous, especially when driving or operating heavy machinery.

There are two types of narcolepsy. Type 1 involves cataplexy and accounts for about 20% of cases, while Type 2 does not and makes up the majority of cases. The causes of narcolepsy depend on the type, but they are linked to the hypothalamus, the part of the brain that regulates sleep and wake times.

Narcolepsy is usually treated with medication, changes to daily routine, or a combination of both. Medications include wakefulness-promoting drugs, antidepressants, and sodium oxybate. Lifestyle changes include scheduled napping, a consistent sleep schedule, avoiding caffeine and alcohol, and regular exercise.

While there is no cure for narcolepsy, treatment options can help reduce symptoms and improve quality of life. However, it is important to note that treatment may not completely eliminate excessive daytime sleepiness, and side effects from medications may occur.

Narcolepsy is not dangerous but can create dangerous situations

Narcolepsy is a chronic neurological disorder that affects the brain's ability to control sleep-wake cycles. While narcolepsy itself is not dangerous, it can create dangerous situations. People with narcolepsy may experience "sleep attacks", where they fall asleep for short periods unintentionally, despite fighting the urge to sleep. These sleep attacks may happen at inappropriate or potentially dangerous times, such as in the middle of daily activities like walking, eating, or driving.

Narcolepsy is characterised by excessive daytime sleepiness (EDS), which is often the most obvious symptom. Everyone with narcolepsy has some level of daytime sleepiness, but the severity varies among individuals. Sleepiness in narcolepsy is often like a "sleep attack", where an overwhelming feeling of sleepiness comes on quickly. In between sleep attacks, individuals can have normal levels of alertness, particularly if they are doing activities that keep their attention.

Narcolepsy can also cause sleep paralysis, a temporary inability to move or speak while falling asleep or waking up, which usually lasts only a few seconds or minutes. Sleep paralysis is similar to cataplexy, except that it occurs at the edges of sleep. Very vivid dreamlike and sometimes frightening visual, auditory, or tactile hallucinations can accompany sleep paralysis and usually occur when people are falling asleep or waking up.

Another symptom of narcolepsy is fragmented nighttime sleep and insomnia. While individuals with narcolepsy are very sleepy during the day, they usually also experience difficulties staying asleep at night. They may wake up several times each night for 10-20 minutes, which can worsen daytime sleepiness. Sleep may be disrupted by insomnia, vivid dreaming, sleep apnea, acting out dreams, and periodic leg movements.

Narcolepsy can greatly affect daily activities. If left undiagnosed or untreated, it can interfere with emotional well-being, social interactions, and the ability to think clearly, which can impact school, work, and social life. Even with treatment, people with narcolepsy may still experience daytime sleepiness and depression.

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