Sleep is an integral part of our physical and mental well being. Deficiency in sleep can be caused by a multitude of factors including parasomnia, a condition where unpleasant or abnormal behaviours occur during sleep. This often exists without the knowledge of those afflicted. Here are 5 rare sleep disorders that may send a chill down your spine.

1) REM Sleep Behavior Disorder (RBD)

Dreaming, for most people, is an epiphenomenon that occurs only in the mind while the body is at rest. Patients with RBD however, engage in their dreams physically by moving their limbs, getting up or expressing themselves verbally without being completely aware of it. With normal REM sleep, skeletal muscles are being inhibited, resulting in temporary muscle paralysis. This inhibition may become impaired in RBD, causing sufferers to enact in their dreams. RBD can be potentially dangerous as patients may become violent subconsciously, resulting in undue injuries to themselves, sleeping partners or people they encounter.

2) Sexsomnia

Sexsomnia or sleep sex, is a type of parasomnia characterized by uncontrolled sexual act during sleep, including moaning, body thrusting and self-pleasuring. As it occurs during the deepest stage of sleep, subjects are usually unaware of the condition unless observed by their sleep partners.

3) Somnambulistic Eating

Somnambulistic eating, also known as sleep-related eating disorder (SRED), involves episodes of eating, often excessively, in the middle of a nighttime sleep. Similar to sleepwalking, individuals afflicted with SRED are unaware of their activities and have no recollection of its occurrence. Whilst it is usually difficult to rouse them from their state, SRED sufferers will usually return to bed once their eating episodes are completed.

4) Sleepdriving

Sleepdriving, is a sleep-related automatic complex behaviour, often associated with the ingestion of hypnotics such as zolpidem. Similar to other instances of parasomnias, afflicted individuals typically have no recollection of the incidence. A case series involving eight clinical patients and six legal defendants was conducted to describe zolpidem-associated complex behaviors. The study published in the Journal of Clinical Sleep Medicines shows that high doses of zolpidem, ingestion outside bedtime and concomitant intake of other sedatives amongst others, increases the risk of sleepdriving and daytime automatisms.

5) Hypnagogic and Hypnopompic Hallucinations

During wake-sleep transition, some people may encounter vivid hallucination while having the sensation of being physically immobile even though they are partially conscious. Hypnagogic which occurs during sleep onsets and hypnopompic during awakening, often involves vivid and frightening episodes of lucid images, strange noises or phantom sensations. They are often associated with sleep paralysis, leaving subjects with the feeling of muscle tightness, falling sensation or inability to move. MIMS

1) National Sleep Foundation (2016). [online] Available at: [Accessed 17 Jul. 2016].
2) American Sleep Association, (2016). [online] Available at: [Accessed 17 Jul. 2016].
3) Poceta JS. Zolpidem Ingestion, Automatisms, and Sleep Driving: A Clinical and Legal Case Series. Journal of Clinical Sleep Medicine : JCSM : Official Publication of the American Academy of Sleep Medicine. 2011;7(6):632-638. doi:10.5664/jcsm.1468.

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