The girl who was too afraid to sleep
Ann (name changed), a 24-year-old software engineer, consulted me a year ago. When she walked through my clinic door, I saw an anxious, fatigued girl, who came in with her mother. Right from the start of the encounter, it was clear that she had little hope of being listened to, having a "why should I even bother telling you what I'm going through, when I know you will think I'm crazy" look on her face. Yet, being prodded by her mother, she told me that she was terrified of falling asleep. Almost every single night, especially at the start of the night, she would wake up with a sense of impending doom. She would be awake, with a clear awareness of her surroundings, with a feeling of a weight placed on her chest, and an inability to move any part of her body to overcome or resist the feeling. She would feel suffocated, would break out into a cold sweat, and feel overwhelmed by the helplessness of her situation. She would feel a presence in her room, being unable to clearly define the shape or form of the presence. She would sometimes start screaming hysterically, being eventually calmed by her parents, who would rush to the sound of her screams. These were the better nights; the worse nights were the ones in which she would want to, but be unable to scream, or sometimes even open her eyes. These episodes, according to her mother, would typically last a couple of minutes, but to Ann, they seemed like forever.
What is sleep paralysis?
Sleep paralysis has been defined by the International Classification of Sleep Disorders (ICSD-3) as “a disturbing temporary inability to perform voluntary movements at sleep-wake transitions. Despite being awake and conscious of the sleeping environment, it is impossible for subjects to move their limbs or even open their eyes. The experience can last for several minutes. Other symptoms can include blurred vision, and double vision.” Hallucinations can accompany the paralysis in 25-75 per cent of such episodes. Among hallucinations, three themes appear common: intruder hallucinations (sense of an evil or malevolent presence in the room), incubus hallucinations (being suffocated or choked), and vestibular hallucinations (the out-of-body, or floating experiences).
Why does sleep paralysis occur?
Sleep is divided into the lighter non-rapid eye-movement (NREM) sleep, and the deeper REM sleep. REM sleep, the stage in which dreams occur, is characterised by a complete paralysis of the voluntary muscles of the body, which prevents an individual from acting out one's dreams and harming oneself. Sleep paralysis is thought to occur due to a REM-intrusion into wakefulness, i.e. the body is still in REM sleep, while the brain has woken up.
How common is sleep paralysis?
The prevalence of sleep paralysis in India is unknown, as sleep medicine is an under-researched faculty in India. Most international studies have reported that around 8-10% of the general population reports at least one episode of sleep paralysis in their lifetime.
This prevalence appears to be higher among students, and those with psychiatric illness (anxiety disorder, panic disorder, post-traumatic stress disorder), possibly reflecting the contribution of sleep deprivation in the former, and sleep disorders in the latter group of individuals. Stressful life events, shift-work, and jetlag are other factors that have been associated with sleep paralysis, while a rarer condition called narcolepsy needs to be looked for in individuals with frequent such episodes.
How does one diagnose the cause?
As sleep paralysis is not recognized among individuals as a genuine symptom, and most physicians are not aware of the entity, those who suffer from the condition often seek a paranormal explanation, and end up attempting to find spiritual cures. I have had patients who have had their houses blessed by holy men, cleansing rituals and "exorcisms" performed on them before seeking medical help. A detailed sleep history is the first step in identifying the potential cause of recurrent sleep paralysis, as poor sleep hygiene, sleep deprivation and frequent awakenings are often the commonest association. In young adults, ensuring an adequate duration of sleep with a regular schedule, limiting exposures to bright lights (including back-lit devices such as mobile phones), and avoiding caffeine is the first step. Screening for, and diagnosing underlying psychiatric causes are important, as is identifying stressors (psychological and/or sexual abuse has been associated with the condition). Narcolepsy is a rare disorder associated with excessive sleepiness during the day, including "sleep attacks", cataplexy (loss of balance/ falls during periods of emotional excitement), and is often associated with recurrent episodes of sleep paralysis.
Back to the girl who was too afraid to sleep:
On enquiry, Ann told me that she had injured herself on more than one occasion as a consequence of "her knees giving way" during episodes of intense laughter or crying. Her friends also told her that she often "phased out" during conversations, with having no recollection of these episodes after. She had a regular sleep schedule, and did not appear to have any underlying stressors or signs of a psychiatric illness. My clinical diagnosis was that of narcolepsy, and further studies (which included actigraphy, a polysomnography and a multiple sleep latency test) confirmed the diagnosis. I prescribed a stimulant medication, and worked with her employer to schedule short daytime naps, and she improved significantly with treatment.
How does one treat sleep paralysis?
Unlike Ann, most individuals with sleep paralysis will have simpler, commoner causes. Reassuring the individual that these episodes are innocuous, emphasizing the need for a regular sleep schedule, and treatment of underlying anxiety is often all that is needed. During the episode, trying to focus on moving the distal parts of the body such as fingers and toes, rather than the entire body, has been found to help, and sleeping on one's side, rather than one's back has been associated with a reduction in frequency of episodes. Keeping a pleasant picture on the ceiling and walls to focus on during the episodes can also help, with the repeated reassurance that these episodes pass away in a few minutes.
The first step, however, to help individuals with what seems to be a relatively common condition, is to spread awareness about the condition, and to encourage individuals to seek professional help for sleep paralysis, especially if the episodes are recurrent.
The writer Consultant respirologist with PD Hinduja Hospital & Medical Research Centre, Mumbai