What is narcolepsy?

Narcolepsy is a condition that affects approximately .05% of the population. In the UK that means 25,000 people are affected by Narcolepsy, which is almost the same figure as those affected by Type 2 Diabetes and probably more than those affected by Parkinson’s. As Narcolepsy is a relatively rare sleep disorder it is known as an ‘orphan disease’ this means it a disease that affects less than 5 per 10,000 people within a community. Narcolepsy is a sleep disorder which affects the brains’ ability to regulate the normal sleep-wake cycle. This can lead to symptoms such as disturbed night-time sleep and excessive sleepiness throughout the day.

The sleep/wake cycle

Normal sleep is organised into a regular pattern of REM (Rapid Eye Movement) and non-REM stages. Every 90 minutes or so, a normal sleeper experiences several minutes of REM sleep where dreaming occurs before switching back to non-REM sleep.

In narcoleptic sufferers however, the nocturnal sleep pattern is much more fragmented and they typically experience numerous awakenings. REM sleep can occur very quickly during the night or day, producing unusual phenomena such as hallucinations.

Key symptoms

Disturbed night-time sleep	This is a common and often under recognised symptom of narcolepsy A fragmented sleep pattern leads to frequent awakenings throughout the night and an unrefreshed feeling in the morning
Excessive sleepiness (ES)	This refers to falling asleep at inappropriate times throughout the day and/or the experiencing of chronic pervasive sleepiness and fatigue Excessive sleepiness will also produce poor concentration and attention with effects on short term memory. At least part of the sleepiness may be secondary to disturbed night-time sleep
Cataplexy	Cataplexy is the most specific symptom in narcolepsy but it doesn’t appear in all patients. Around a third will not have cataplexy Cataplexy attacks involve a temporary voluntary muscle weakness in response to emotions or the anticipation of emotion. Positive emotions such as laughter are the most potent triggers although anger, fear, embarrassment and surprise may also provoke attacks in some The severity of a cataplexy attack can vary from mild facial weakness to the buckling of the knees and collapse whilst still remaining conscious Cataplexy attacks can last for seconds or up to two minutes and can occur repeatedly for up to 20 – 60 minutes
Sleep paralysis	An inability to move while being conscious either at the onset of falling asleep or when waking from sleep This usually lasts for a couple of minutes but can last for up to 30 minutes
Hypnagogic / hypnopomic hallucinations	These are vivid, frequently frightening dream-like experiences which occur during the transition between sleep and wakefulness They may accompany sleep paralysis
Other symptoms	Automatic behaviour involves carrying on with an activity even though you have no recollection of it. You are not aware of your actions and don’t perform them well. For example, if you're writing before falling asleep, you may scribble rather than form word Many narcoleptics report problems with food. This could be over or under eating or being intolerant to many standard food groups There appears to be an increased incidence of hyper activity in children diagnosed with narcolepsy. Their activities seem to speed up rather than slow down.
Secondary narcolepsy	Narcolepsy which occurs because of an additional, underlying neurological condition such as Parkinson’s Disease, Myotonic Dystrophy or Traumatic Brain Injury Secondary narcoleptics also suffer from daytime excessive sleepiness, disturbed night-time sleep and occasionally cataplexy attacks It is usually possible to identify damage to the hypocretin system in the hypothalamus that controls the sleep-wake cycle as opposed to primary narcolepsy where the ultimate cause is currently unknown

Other possible features include:

Low mood anxiety and depression
Social introversion / psychosocial problems
Increasingly sedentary lifestyle

(See recognising narcolepsy for further information)