Narcolepsy - Wikipedia, the free encyclopedia
Normally, when an individual is awake, brain waves show a regular rhythm. When a person first falls asleep, the brain waves become slower and less regular. This sleep state is called non-rapid eye movement (NREM) sleep. After about an hour and a half of NREM sleep, the brain waves begin to show a more active pattern again. This sleep state, called rapid eye movement (REM) sleep, is when most remembered dreaming occurs.
In narcolepsy, the order and length of NREM and REM sleep periods are disturbed, with REM sleep occurring at sleep onset instead of after a period of NREM sleep. Thus, narcolepsy is a disorder in which REM sleep appears at an abnormal time. Also, some of the aspects of REM sleep that normally occur only during sleep -- lack of muscular control, sleep paralysis, and vivid dreams -- occur at other times in people with narcolepsy. For example, the lack of muscular control can occur during wakefulness in a cataplexy episode. Sleep paralysis and vivid dreams can occur while falling asleep or waking up.Simply put, the brain does not pass through the normal stages of dozing and deep sleep but goes directly into (and out of) rapid eye movement (REM) sleep. This has several consequences:
Nighttime sleep does not include much deep sleep, so the brain tries to "catch up" during the day, hence EDS
May visibly fall asleep at any moment (such motions as head bobbing are common)
People with narcolepsy fall quickly into what appears to be very deep sleep
They wake up suddenly and can be disoriented when they do (dizziness is a common occurrence)
They have very vivid dreams, which they often remember
People with narcolepsy may dream even when they only fall asleep for a few seconds.
I do that. I take a nap and go right into dreaming. I wake up from a dream and it is disorientating. I can go back to sleep and go right back to the dream.
Causes
While the cause of narcolepsy has not yet been determined, scientists have discovered conditions that may increase an individual's risk of having the disorder. Specifically, there appears to be a strong link between narcoleptic individuals and certain genetic conditions. One factor that may predispose an individual to narcolepsy involves an area of Chromosome 6 known as the HLA complex. There appears to be a correlation between narcoleptic individuals and certain variations in HLA genes, although it is not required for the condition to occur.
Certain variations in the HLA complex are thought to increase the risk of an auto-immune response to protein producing neurons in the brain. The protein produced, called hypocretin or orexin, is responsible for controlling appetite and sleep patterns. Individuals with narcolepsy often have reduced numbers of these protein-producing neurons in their brains.
The neural control of normal sleep states and the relationship to narcolepsy are only partially understood. In humans, narcoleptic sleep is characterized by a tendency to go abruptly from a waking state to REM sleep with little or no intervening non-REM sleep. The changes in the motor and proprioceptive systems during REM sleep have been studied in both human and animal models. During normal REM sleep, spinal and brainstem alpha motor neuron hypopolarization produces almost complete atonia of skeletal muscles via an inhibitory descending reticulospinal pathway. Acetylcholine may be one of the neurotransmitters involved in this pathway. In narcolepsy, the reflex inhibition of the motor system seen in cataplexy is believed identical to that seen in normal REM sleep.[citation needed]
In 2004 researchers in Australia induced narcolepsy-like symptoms in mice by injecting them with antibodies from narcoleptic humans. The research has been published in the Lancet providing strong evidence suggesting that some cases of narcolepsy might be caused by autoimmune disease.[1]
Narcolepsy is strongly associated with HLA DQB1*0602 genotype
I have that, but 15% of the population does also.
Normally, when an individual is awake, brain waves show a regular rhythm. When a person first falls asleep, the brain waves become slower and less regular. This sleep state is called non-rapid eye movement (NREM) sleep. After about an hour and a half of NREM sleep, the brain waves begin to show a more active pattern again. This sleep state, called rapid eye movement (REM) sleep, is when most remembered dreaming occurs.
In narcolepsy, the order and length of NREM and REM sleep periods are disturbed, with REM sleep occurring at sleep onset instead of after a period of NREM sleep. Thus, narcolepsy is a disorder in which REM sleep appears at an abnormal time. Also, some of the aspects of REM sleep that normally occur only during sleep -- lack of muscular control, sleep paralysis, and vivid dreams -- occur at other times in people with narcolepsy. For example, the lack of muscular control can occur during wakefulness in a cataplexy episode. Sleep paralysis and vivid dreams can occur while falling asleep or waking up.Simply put, the brain does not pass through the normal stages of dozing and deep sleep but goes directly into (and out of) rapid eye movement (REM) sleep. This has several consequences:
Nighttime sleep does not include much deep sleep, so the brain tries to "catch up" during the day, hence EDS
May visibly fall asleep at any moment (such motions as head bobbing are common)
People with narcolepsy fall quickly into what appears to be very deep sleep
They wake up suddenly and can be disoriented when they do (dizziness is a common occurrence)
They have very vivid dreams, which they often remember
People with narcolepsy may dream even when they only fall asleep for a few seconds.
I do that. I take a nap and go right into dreaming. I wake up from a dream and it is disorientating. I can go back to sleep and go right back to the dream.
Causes
While the cause of narcolepsy has not yet been determined, scientists have discovered conditions that may increase an individual's risk of having the disorder. Specifically, there appears to be a strong link between narcoleptic individuals and certain genetic conditions. One factor that may predispose an individual to narcolepsy involves an area of Chromosome 6 known as the HLA complex. There appears to be a correlation between narcoleptic individuals and certain variations in HLA genes, although it is not required for the condition to occur.
Certain variations in the HLA complex are thought to increase the risk of an auto-immune response to protein producing neurons in the brain. The protein produced, called hypocretin or orexin, is responsible for controlling appetite and sleep patterns. Individuals with narcolepsy often have reduced numbers of these protein-producing neurons in their brains.
The neural control of normal sleep states and the relationship to narcolepsy are only partially understood. In humans, narcoleptic sleep is characterized by a tendency to go abruptly from a waking state to REM sleep with little or no intervening non-REM sleep. The changes in the motor and proprioceptive systems during REM sleep have been studied in both human and animal models. During normal REM sleep, spinal and brainstem alpha motor neuron hypopolarization produces almost complete atonia of skeletal muscles via an inhibitory descending reticulospinal pathway. Acetylcholine may be one of the neurotransmitters involved in this pathway. In narcolepsy, the reflex inhibition of the motor system seen in cataplexy is believed identical to that seen in normal REM sleep.[citation needed]
In 2004 researchers in Australia induced narcolepsy-like symptoms in mice by injecting them with antibodies from narcoleptic humans. The research has been published in the Lancet providing strong evidence suggesting that some cases of narcolepsy might be caused by autoimmune disease.[1]
Narcolepsy is strongly associated with HLA DQB1*0602 genotype
I have that, but 15% of the population does also.
Comments