In a typical sleep cycle, we initially enter the early stages of sleep followed by deeper sleep stages and ultimately (after about 90 minutes) rapid eye movement (REM) sleep. For people suffering from narcolepsy, REM sleep occurs almost immediately in the sleep cycle as well as periodically during the waking hours. It is in REM sleep that we can experience dreams and muscle paralysis which explains some of the symptoms of narcolepsy.

Narcolepsy usually begins between the ages of 15 and 25, but it can become apparent at any age. In many cases, narcolepsy is undiagnosed and, therefore, untreated.

What Causes Narcolepsy?

The cause of narcolepsy is not known; however, scientists have made progress toward identifying genes strongly associated with the disorder. These genes control the production of chemicals in the brain that may signal sleep and awake cycles. Some experts think narcolepsy may be due to a deficiency in the production of a chemical called hypocretin by the brain. In addition, researchers have discovered abnormalities in various parts of the brain involved in regulating REM sleep. These abnormalities apparently contribute to symptom development. According to experts, it is likely narcolepsy involves multiple factors that interact to cause neurological dysfunction and REM sleep disturbances.
What Are the Symptoms of Narcolepsy?

Symptoms of narcolepsy include:

* Excessive daytime sleepiness (EDS): In general, EDS interferes with normal activities on a daily basis, whether or not a person with narcolepsy has sufficient sleep at night. People with EDS report mental cloudiness, a lack of energy and concentration, memory lapses, a depressed mood, and/or extreme exhaustion.
* Cataplexy: This symptom consists of a sudden loss of muscle tone that leads to feelings of weakness and a loss of voluntary muscle control. It can cause symptoms ranging from slurred speech to total body collapse depending on the muscles involved and is often triggered by intense emotion, for example surprise, laughter, or anger.
* Hallucinations: Usually, these delusional experiences are vivid and frequently they are frightening. The content is primarily visual, but any of the other senses can be involved. These are called hypnagogic hallucinations when accompanying sleep onset and hypnopompic hallucinations when occurring during awakening.
* Sleep paralysis: This symptom involves the temporary inability to move or speak while falling asleep or waking up. These episodes are generally brief lasting a few seconds to several minutes. After episodes end, people rapidly recover their full capacity to move and speak.

How Is Narcolepsy Diagnosed?

A clinical examination and exhaustive medical history are essential for proper diagnosis of narcolepsy. However, none of the major symptoms is exclusive to narcolepsy. Several specialized tests, which can be performed in a sleep disorders clinic, usually are required before a diagnosis can be established. Two tests that are considered essential in confirming a diagnosis of narcolepsy are the polysomnogram (PSG) and the multiple sleep latency test (MSLT).

The PSG is an overnight test that takes continuous multiple measurements while a patient is asleep to document abnormalities in the sleep cycle. A PSG can help reveal whether REM sleep occurs at abnormal times in the sleep cycle and can eliminate the possibility that an individual’s symptoms result from another condition.

The MSLT is performed during the day to measure a person’s tendency to fall asleep and to determine whether isolated elements of REM sleep intrude at inappropriate times during the waking hours. As part of the test, an individual is asked to take four or five short naps usually scheduled two hours apart.
How Is Narcolepsy Treated?

Although there is no cure for narcolepsy, the most disabling symptoms of the disorder (EDS and symptoms of abnormal REM sleep, such as cataplexy) can be controlled in most people with drug treatment. Sleepiness is treated with amphetamine-like stimulants while the symptoms of abnormal REM sleep are treated using antidepressant medications.

There has recently been a new medication approved for those who suffer from narcolepsy with cataplexy. This medication, called Xyrem, helps people with narcolepsy get a better night’s sleep, allowing them to be less sleepy during the day. Patients with narcolepsy can be substantially helped — but not cured — by medical treatment.

Lifestyle adjustments such as avoiding caffeine, alcohol, nicotine, and heavy meals, regulating sleep schedules, scheduling daytime naps (10-15 minutes in length), and establishing a normal exercise and meal schedule may also help to reduce symptoms.

• Infants require about 16 hours a day
• Teenagers need about 9 hours on average
• Most adults need 7 to 8 hours a night for the best amount of sleep, although some people may need as few as 5 hours or as many as 10 hours of sleep each day
• Women in the first 3 months of pregnancy often need several more hours of sleep than usual

However, experts say that if you feel drowsy during the day, even during boring activities, you haven’t had enough sleep.

Sleep Deprivation Debits

The amount of sleep a person needs also increases if he or she has been deprived of sleep in previous days. Getting too little sleep creates a “sleep debt,” which is much like being overdrawn at a bank. Eventually, your body will demand that the debt be repaid. We don’t seem to adapt to getting less sleep than we need, while we may get used to a sleep-depriving schedule, our judgment, reaction time, and other functions are still impaired.

Consequences of Too Little Sleep

Too little sleep may cause:

• Memory problems
• Depression
• A weakening of your immune system, increasing your chance of becoming sick
• Increase in perception of pain

Sleep Deprivation Risky Business

Many studies make it clear that sleep deprivation is dangerous. Sleep-deprived people who are tested by using a driving simulator or by performing a hand-eye coordination task perform as badly as or worse than those who are intoxicated.

Sleep deprivation also magnifies alcohol’s effects on the body, so a fatigued person who drinks will become much more impaired than someone who is well rested.

Driver fatigue is responsible for an estimated 100,000 motor vehicle accidents and 1,500 deaths each year, according to the National Highway Traffic Safety Administration. Since drowsiness is the brain’s last step before falling asleep, driving while drowsy can — and often does — lead to disaster. Caffeine and other stimulants cannot overcome the effects of severe sleep deprivation.

The National Sleep Foundation says that if you have trouble keeping your eyes focused, if you can’t stop yawning, or if you can’t remember driving the last few miles, you are probably too drowsy to drive safely.

What Happens During Sleep?

Sleep is prompted by natural cycles of activity in the brain and consists of two basic states: rapid eye movement (REM) sleep and non-rapid eye movement (NREM) sleep, which consists of Stages 1 through 4.

During sleep, the body cycles between non-REM and REM sleep. Typically, people begin the sleep cycle with a period of non-REM sleep followed by a very short period of REM sleep. Dreams generally occur in the REM stage of sleep.

What Is Non-REM Sleep?

The period of NREM sleep is made up of stages 1-4. Each stage can last from 5 to 15 minutes. A completed cycle of sleep consists of a progression from stages 1-4 before REM sleep is attained, then the cycle starts over again.

• Stage 1: Polysomnography (sleep readings) shows a reduction in activity between wakefulness and stage 1 sleep. The eyes are closed during Stage 1 sleep. One can be awakened without difficulty, however, if aroused from this stage of sleep, a person may feel as if he or she has not slept. Stage 1 may last for five to 10 minutes. Many may notice the feeling of falling during this stage of sleep, which may cause a sudden muscle contraction (called hypnic myoclonia).
• Stage 2: This is a period of light sleep during which polysomnographic readings show intermittent peaks and valleys, or positive and negative waves. These waves indicate spontaneous periods of muscle tone mixed with periods of muscle relaxation. The heart rate slows and the body temperature decreases. At this point, the body prepares to enter deep sleep.
• Stages 3 and 4: These are deep sleep stages, with stage 4 being more intense than Stage 3. These stages are known as slow-wave, or delta, sleep. If aroused from sleep during these stages, a person may feel disoriented for a few minutes.

During the deep stages of NREM sleep, the body repairs and regenerates tissues, builds bone and muscle, and appears to strengthen the immune system. As you get older, you sleep more lightly and get less deep sleep. Aging is also associated with shorter time spans of sleep, although studies show the amount of sleep needed doesn’t appear to diminish with age.

What Is REM Sleep?

Usually, REM sleep occurs 90 minutes after sleep onset. The first period of REM typically lasts 10 minutes, with each recurring REM stage lengthening, and the final one may last up to an hour. Polysomnograms show brainwave patterns in REM to be similar to that recorded during wakefulness. In people without sleep disorders, heart rate and respiration speed up and become erratic during REM sleep. During this stage the eyes move rapidly in different directions.

Intense dreaming occurs during REM sleep as a result of heightened brain activity, but paralysis occurs simultaneously in the major voluntary muscle groups. REM is a mixture of encephalic (brain) states of excitement and muscular immobility. For this reason, it is sometimes called paradoxical sleep.

The percentage of REM sleep is highest during infancy and early childhood. During adolescence and young adulthood, the percentage of REM sleep declines. Infants can spend up to 50% of their sleep in the REM stage of sleep, whereas adults spend only about 20% in REM.

How Much Sleep Do You Need?

The amount of sleep a person needs depends on the individual. The need for sleep depends on various factors, one of which is age. Infants usually require about 16-18 hours of sleep per day, while teenagers need about 9 hours per day on average. Most adults need about 7-8 hours of sleep per day.

The amount of sleep a person needs also increases if he or she has been deprived of sleep. People do not seem to adapt to getting less sleep than they need.

What Are the Consequences of Too Little Sleep?

Too little sleep may cause:

• Impaired memory and thought processes.
• Depression.
• Decreased immune response.

Sleep deprivation also magnifies alcohols effects on the body, so a fatigued person who drinks will become much more impaired than someone who is well-rested. Sleep deprivation also increases pain perception on pain simulation testing. Caffeine and other stimulants can temporarily overcome the effects of severe sleep deprivation, but cannot do so for extended periods of time.