1. Nightmare disorder: When the occasional nightmare becomes a common problem, so you wake up in a sweat or you’re afraid to go to sleep, then you could be suffering from nightmare disorder. According to the American Sleep Association, stress and sleep deprivation are the main triggers for this disorder.
2. Sleep walking: The causes of sleep walking are not fully known – although genetics, broken sleep and stress are thought to play a role. Sleepwalkers open doors, move their furniture around, and move from room to room with no trouble at all. According to the Journal of Molecular Psychiatry, 19 percent of adult sleepwalkers have been injured while sleep walking. The main risks are tripping and falling.
3. Exploding head syndrome: This disorder occurs at the onset of deep sleep, when a loud noise awakens up someone who’s just fallen asleep. These sounds range from explosives going off inside their head, to cymbals crashing loudly, right next to their bed. Of course, there’s no actual sound – so it’s all a mystery. The person’s not at risk - and there’s no obvious cause.
4. Hypnagogic hallucinations: These occur as the person is falling sleep or at the end of the night as they start to waken up. The person’s sure they can hear voices, or they experience strange sensations, or they report seeing people or weird objects in the room. A common vision sufferers have is seeing small animals or thinking they see bugs crawling over the walls. According to the American Sleep Association, these kinds of sleep-related hallucinations are most frequently reported in people with narcolepsy.
5. Night terrors: This is where the person (and most commonly a child) starts to scream, thrash around, or to pace about the room. However, they can’t be wakened up or be comforted. They are trapped in this world that is threatening to them. Night terrors are different from nightmares as they occur in non-REM sleep (the deepest type of sleep that occurs early at night). Although the cause is still unknown, fever and stress may play a role.
6. Sleep paralysis: This occurs in REM sleep, later on in the night, when the person is having a very vivid dream - but is also temporarily immobilised. Thus, although they want to move or to quickly run away they find they’re paralysed, and are rooted to the spot. Often sleep paralysis and sleep hallucinations occur simultaneously. Common images and sensations include sensing an evil presence in the room, or feeling they’re being crushed or choked. In Newfoundland, Canada, this is known as the “Old Hag"; in China, it’s called “the ghost pressing down on you"; and in Mexico, it is described as being “the dead climbing on top of you.“
7. REM behaviour disorder: This occurs during REM sleep, where the sleeper starts to act out the content of their dreams. Thus, they may get out of bed and then start to run around; or they may scream and yell, or they may start to get dressed. It is seen most in older adults, and especially in those who’ve been diagnosed with Parkinson’s disease.
8. Nocturnal eating disorder: People diagnosed with this sleep disorder go on eating binges when they’re fast asleep. Some chop up meat and vegetables, or turn on the stove, and then go back to bed without tidying up the mess. Others eat raw foods like onions or fresh meat, or they eat frozen food or unusual types of food (like margarine straight from the margarine tub). Like sleepwalking, it occurs during non-REM sleep. There is no known cause.