Sleep Paralysis

Patients will usually present with bouts of paralysis in periods before sleeping and before awakening. They are unable to move, speak and react in this transition which usually last for a few seconds to a few minutes. This paralysis spells conclude on their own or when the patient is touched or moved. The characteristic hypnogogic and hypnopompic hallucinations are often seen in sleep paralysis and are often revered as a terrifying experience in most patients.

The diagnosis of sleep paralysis is reached when all other sleep disorders that potentially give rise to paralysis have been ruled out. The most common medical condition investigated upon with sleep paralysis is narcolepsy which actually includes sleep paralysis as one of its major diagnostic criteria. The following sleep study tests and diagnostic modalities are implored in the investigation of sleep paralysis:

• Nocturnal polysomnography: This device records the lung, heart, and brain activities during sleep. Breathing patterns are graphed while nocturnal patterns of arm and leg movements are also recorded. The blood oxygen levels are measured during the test process to assess the clinical impact of sleep paralysis or narcolepsy on the patient.
• Home sleep test kits: These test kits are very similar to the nocturnal polysomnograph, although only the heart rate, breathing patterns, airflow, and blood oxygen saturation are the only parameters which are being measured. Sleep experts may accompany the patient at home and makes a detailed observation of the sleep paralysis event. 

In the majority of patients suffering from sleep paralysis, treatment may not be required because it is clinically benign. For cases where the underlying causes are identified like the lack of sleep, some lifestyle modifications may be effected to increase the duration of sleep to avert the paralytic spells [8]. Patients having a mental health condition suffering from sleep paralysis may benefit from pharmacotherapy, psychotherapy, and family support that greatly reduces the incidence of the disorder. In severe cases of sleep paralysis, tricyclic antidepressants and selective serotonin reuptake inhibitors (SSRI) are commonly given to control the recurrence of the disorder [9].

Although the experience of sleep paralysis is adjudged to be most dreadful and terrifying to most subjects, there has been no scientific evidences linking it to serious medical events or disorders. Sleep paralysis has a good prognostic outlook for all cases.

Physiologically, muscles relax and becomes periodically paralyzed during normal sleep patterns. In some instances, these mechanisms of paralysis may temporarily persists during the transition of awakenings. Moreover, there are many events or risk factors that increase the likelihood for the development of sleep paralysis. Among these:

• Irregular sleeping patterns
• Sleep deprivation
• Teenager and young adults
• Narcolepsy
• Strong familial history

Among patients diagnosed with narcolepsy, 30 to 50% have experienced a form of isolated sleep paralysis [1]. Sleep paralysis has a worldwide incidence of 6.2% of the population, with any of them experiencing a paralytic attack of at least once a month or once a year. Of these patients, only 3% suffers from recurrent isolated sleep paralysis (RISP) which is a type of sleep paralysis that occurs nightly [2]. There is no sexual predilection in sleep paralysis. The adolescents and the young adult’s age group are more prone to sleep paralysis compared to any other age segments. The prevalence of sleep paralysis peaks at a mean age of 25 to 44 years old, representing 36% of all the cases recorded [3].

The researches done in sleep sciences have afforded several theories in the pathogenesis of sleep paralysis. The more common theories links sleep paralysis as a type of parasomnia or sleep walking which emanates from the dysfunctional overlap of the rapid eye movement (REM) stage of sleep and the waking stage of sleep [4]. Some current polysomnographic studies have made observations that any disturbances done in the regular sleeping pattern can induce sleep paralysis among its respondents [5].

Another major theory postulates that sleep paralysis stems out as a result of the neural signaling imbalances between the cholinergic neural populations that facilitates wakefulness and the serotonergic neural populations that maintains normal sleep [6]. The patterns of REM sleep fragmentations and the occurrence of hypnogogic and hypnopompic hallucinations among family lines have catered the idea that isolated sleep paralysis may involve genetic mechanisms in its pathogenesis [7].

Patients who are at risk of sleep paralysis may extend their sleeping hours to prevent its recurrence. One should avoid stimulants like alcohol, tobacco and recreational drugs that may alter one’s sleeping patterns. Patients are strongly advised to stay supine during sleep to reduce attacks of sleep paralysis and lessen the upper airway obstructions [10].

Sleep paralysis is a dreadful form of paralysis that clinically occurs upon waking up or just before going to sleep. Patients who undergone sleep paralysis complain of sensation of noise, olfaction, levitation and paralysis during the attacks. Sleep paralysis is not usually associated with a severe medical condition but the whole event will usually be frightening to the patient. Sleep paralysis occurs either before falling asleep which is also referred to as hypnogogic sleep paralysis or predormital sleep paralysis, or just before waking up otherwise known as hypnopompic or postdormital sleep paralysis.

Definition

Sleep paralysis is a dreadful and terrifying form of paralysis that periodically occurs upon waking up or just before going to sleep.

Cause

Sleep paralysis is commonly seen among the young adult population with high familial tendencies. Patients with variable sleeping patterns and those who have some form of sleep deprivation may also be prone to the disease.

Symptoms

The disorder occurs in the period just before sleeping or in the period just before awakening. Patients may be unable to move, speak, and react to any stimuli within a few seconds or minutes.

Diagnosis

Patients may offer a detailed medical history of the event at home. Sleep studies that makes use of the polysomnographs and the home sleep test kits may elucidate the disorder.

Treatment and follow-up

In majority of cases of sleep paralysis, treatment may never be required. Lifestyle modifications may be done to correct abnormal sleeping patterns. Medications like tricyclic antidepressants and SSRI’s may be given for severe cases of sleep paralysis.

1. Dauvilliers Y, Billiard M, Montplaisir J. Clinical aspects and pathophysiology of narcolepsy". Clinical Neurophysiology 2003 114 (11): 2000–2017.
2. Terrillon J, Marques-Bonham S. Does Recurrent Isolated Sleep Paralysis Involve More Than Cognitive Neurosciences?. Journal of Scientific Exploration 2001 15: 97–123.
3. Ohayon M, Zulley J, Guilleminault C, Smirne S. Prevalence and pathologic associations of sleep paralysis in the general population. Neurology 1999 52 (6): 1194–2000.
4. Goldstein K. Parasomnias. Dis Mon 2011 57 (7): 364–88.
5. Walther B, Schulz H. Recurrent isolated sleep paralysis: Polysomnographic and clinical findings. Somnologie - Schlafforschung und Schlafmedizin 2004 8 (2): 53–60.
6. Cheyne J, Rueffer S, Newby-Clark I. Hypnagogic and Hypnopompic Hallucinations during Sleep Paralysis: Neurological and Cultural Construction of the Night-Mare. Consciousness and Cognition 1999 8 (3): 319–337.
7. Sehgal A, Mignot E. Genetics of Sleep and Sleep Disorders. Cell 2011 146 (2): 194–207.
8. Wills L, Garcia J. Parasomnias: Epidemiology and Management. CNS Drugs. December 2002; 16(12):803-810.
9. Stores G. Medication for sleep-wake disorders. Archives of Disease in Childhood 2003 88 (10): 899–903.
10. Cheyne J. "Situational factors affecting sleep paralysis and associated hallucinations: position and timing effects". Journal of Sleep Research 2002 11 (2): 169–177.