Narcolepsy is a relatively rare or ‘orphan disease’ 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
|
| Automatic behaviours |
- Purposeful or semi-purposeful acts performed during the day without recall, as if on ‘autopilot’
- These acts can vary in length from seconds to minutes
|
| 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)
