Narcolepsy vs. sleep apnea: Similarities and differences - Medical News Today

Narcolepsy and sleep apnea are conditions that can cause someone to feel tired during waking hours. However, their symptoms, causes, and treatments are very different.

Narcolepsy is a rare condition that causes attacks of severe sleepiness, which can happen at any time. Some people also experience a sudden loss of muscle tone, which is known as cataplexy.

In contrast, sleep apnea is a common condition that causes a person's breathing to stop and start during sleep. It can result in tiredness due to low sleep quality.

This article looks at the differences between narcolepsy and sleep apnea, the link between these sleep disorders, and how doctors diagnose them.

Sleep apnea is a common condition that causes a person's breathing to stop or become very shallow temporarily during sleep. Doctors call these instances "breathing pauses," and they can last from a couple of seconds to a couple of minutes.

People with sleep apnea have frequent breathing pauses that can occur 30 times or more per hour. There are several types of sleep apnea, including:

• Obstructive sleep apnea (OSA): This is the most common form of sleep apnea, and it occurs due to a blockage in the upper airways.
• Central sleep apnea: This condition occurs when the brain does not send the signals required for breathing.
• Complex sleep apnea syndrome: This refers to a mix of obstructive and central sleep apnea.

Narcolepsy is a neurological disorder that affects the brain's ability to control its sleep-wake cycle. This can result in people involuntarily and suddenly falling asleep during waking hours, even when they are performing activities that require concentration, such as driving.

It is also common for someone with narcolepsy to experience interrupted sleep due to vivid dreams, hallucinations, or sleep paralysis.

There are two types of narcolepsy: type 1 and type 2. Type 1 occurs with cataplexy, which is a loss of muscle tone. Cataplexy causes part of the body, or the whole body, to become limp. Type 2 occurs without cataplexy.

Narcolepsy symptoms typically start in childhood or young adulthood, but they can begin at any time in life. Many researchers believe that the condition often goes underdiagnosed or misdiagnosed.

The following table compares the symptoms of sleep apnea with those of narcolepsy:

In children, sleep apnea is also associated with bedwetting, worsened asthma, and issues relating to academic performance.

Research suggests that OSA is common among those with narcolepsy. An older 2010 study found that out of 133 people with narcolepsy, 33 individuals — almost 25% — also had sleep apnea symptoms.

However, sleep apnea does not cause narcolepsy. Narcolepsy is a neurological condition that occurs when the brain cannot regulate its sleep-wake cycle.

Doctors are not sure why sleep apnea is common in people who have narcolepsy, but it may be related to the other sleep disruptions that people with narcolepsy often experience.

People with type 1 narcolepsy have low levels of a hormone known as hypocretin. Hypocretin makes a person feel awake, and it regulates rapid eye movement (REM) sleep. Not having enough of this hormone results in excessive sleepiness during waking hours and irregular sleep cycles, which cause symptoms such as vivid dreams.

Doctors are not sure why some people have low levels of hypocretin, but several factors may play a role:

• Autoimmune disease: People with type 1 narcolepsy often have autoimmune conditions, in which the immune system attacks healthy cells. Researchers believe that the immune system may also attack the cells that create hypocretin, leading to a deficiency.
• Family history: In most cases, narcolepsy is not related to a family history of the condition. However, about 10% of people say they have a family member who also has narcolepsy symptoms. This suggests that there may be a genetic component in some cases.
• Brain injury or disease: Rarely, narcolepsy develops after an injury damages an area of the brain that regulates sleep or as a result of another condition that affects the brain, such as a tumor.

People with type 2 narcolepsy usually have normal levels of hypocretin. Researchers have yet to discover what causes this condition.

There are many reasons why a person may feel excessive tiredness during waking hours. Other factors that can contribute to this symptom include:

• insufficient sleep
• insomnia
• hypothyroidism
• depression
• traumatic brain injuries
• certain medications, such as antihistamines, antidepressants, and beta-blockers
• other sleep disorders, such as circadian rhythm disorder

Some more serious conditions can also cause excessive sleepiness, such as Parkinson's disease, multiple sclerosis, and muscular dystrophy. However, these usually produce other symptoms, as well.

A doctor can diagnose the cause of excessive sleepiness, frequent waking during the night, and other symptoms that may indicate sleep apnea or narcolepsy. They will begin the diagnostic process by:

• performing a physical examination
• taking a medical history
• asking the person to keep a sleep journal to record their symptoms

However, sleep studies are the primary method that doctors use to diagnose sleep apnea. A person will sleep overnight at a health center where professionals will observe them and record the number of breathing pauses within an hour. Doctors will also check whether blood oxygen levels change.

If a doctor suspects narcolepsy, they may recommend a combination of a polysomnography (PSG) and a multiple sleep latency test (MSLT).

A PSG is a type of sleep study that tracks breathing, eye movements, brain activity, and muscle movements during sleep. It can detect signs of narcolepsy and other conditions that can affect sleep, including sleep apnea.

An MSLT typically occurs the morning after the PSG. The person will take a nap every 2 hours until they have had five naps in total. This test allows doctors to measure how quickly someone falls asleep and to determine whether they enter REM sleep.

Sometimes, doctors also carry out a lumbar puncture to test the hypocretin levels in a person's cerebrospinal fluid.

Doctors use a range of treatments to address these sleeping disorders.

Sleep apnea treatment

The possible treatments for OSA include:

• lifestyle changes, such as quitting smoking or maintaining a moderate weight
• breathing devices
• mouthpieces
• surgery, if OSA is due to enlarged tonsils or adenoids

The breathing device that doctors most often recommend is a continuous positive air pressure (CPAP) machine. These devices blow pressurized air into the individual's throat to prevent the airway from collapsing.

Mouthpieces for sleep apnea hold the lower jaw forward enough to keep the airway open. If OSA treatment does not help, this could be a sign that someone has another type of sleep apnea, another sleep disorder, or a condition such as narcolepsy.

Narcolepsy treatment

There is no cure for narcolepsy, but medication can help control excessive sleepiness and cataplexy in most people. A doctor may prescribe:

• modafinil (Provigil)
• amphetamine-like stimulants
• tricyclic antidepressants
• selective serotonin reuptake inhibitors
• noradrenergic reuptake inhibitors

An individual may also need to make lifestyle adjustments, such as avoiding caffeine before bed, taking short naps, exercising daily, and maintaining a regular sleep schedule to help manage their symptoms.

Sleep apnea and narcolepsy both cause daytime sleepiness. However, sleep apnea causes tiredness as a result of sleep disturbances, which occur due to frequent pauses in breathing. People with the condition often snore, make gasping or choking noises in their sleep, or wake up with a dry mouth.

Narcolepsy is a neurological disorder that causes intense sleepiness that can lead someone to fall asleep suddenly during daily activities. It can also result in insomnia, vivid dreams, sleep paralysis, and hallucinations. It is possible for someone to have both sleep apnea and narcolepsy, but sleep apnea on its own is far more common.

People who are concerned about their symptoms should consult a doctor for a diagnosis, especially if excessive sleepiness is affecting either their mental health or activities that could be dangerous, such as driving.