31 Oct 2010
Sleep paralysis is a common but distressing experience that can be overcome with enough rest
If you have ever woken to find yourself unable to move or feel a “weight” pressing down on your chest, you need not be overly alarmed.
Studies suggest that many people have experienced sleep paralysis at least once or twice in their lives, with teenagers and young adults being more susceptible. It affects as many as four in 10 people.
The common Chinese term for this condition is gui ya shen, or literally, ghost pressing on body.
But what is the cause?
Dr Ong Thun How, a consultant at Singapore General Hospital, says: “The brain controls the muscles and movements of the body. In the deeper stages of sleep, these signals are inhibited, so the muscles are effectively paralysed.
“Sleep paralysis occurs when your brain wakes up before your body does. The paralysis is usually transient but can be distressing for the individual concerned,” she adds.
The immobility can last from a few minutes to half an hour. You may even find yourself unable to speak.
Computer-graphics artist Chua Kok Hin, 24, has experienced paralysis many times, with days and even months between each episode.
He says: “While your brain is awake, your body refuses to respond and even the eyes can’t open at times.
“And it feels as though you may hurt yourself if you force any part to move.” His solution is simply to go back to sleep or wait for the paralysis, which usually lasts a few minutes, to pass.
Magazine writer Diana Othman, 29, used to experience it often during a stressful period in her undergraduate days, especially when she was exhausted. “I remember feeling as if someone or something sinister was in the room with me, like danger was approaching, which could get pretty scary,” says Ms Diana. She still goes through such experiences a few times a year and forces herself awake when it happens.
She has never consulted a doctor about it as it was common among her friends, and because it did not have any adverse effect on her health.
Dr Chong Yaw Kian, an ENT (ear, nose, throat) consultant who runs the Sleep Clinic at Tan Tock Seng Hospital, notes that some scientists have proposed sleep paralysis as an explanation for alien abductions and ghostly encounters as alleged by some people.
This is because sleep paralysis is sometimes accompanied by frightening hallucinations and visions of “fanciful or dream-like objects”.
These are known as hypnagognic hallucinations. The individual is semi-awake but the brain continues to dream, and so he may still experience vivid dreams.
Other symptoms include sensations of noises or smells.
Indeed, photo editor Nadhirah Kamarudin, 24, who was once “paralysed” for 15 minutes, recalls a “ringing” sound in her ears. But she never saw a doctor about it as it had occurred only a few times .
Dr Chong says: “Sleep paralysis is something normal and physiological so there is no specific medication for it. But treatment starts with identifying and treating the possible predisposing factors, such as excessive alcohol consumption or a very stressful lifestyle.”
Other factors that increase the likelihood of both paralysis and hallucinations are jet lag, sudden environmental and lifestyle changes and substance abuse.
Dr Ong adds: “Sleep paralysis occurs most commonly when a person is sleep-deprived or under stress. Therefore, it’s important to maintain good sleep hygiene – essentially, regular and adequate sleeping hours.”
Dr Chong, who recommends at least six hours of sleep a night, also advises seeing a doctor if the condition leaves you feeling anxious or keeps you awake at night.
He adds: “If the patient experiences it too often, then he should see a doctor to rule out other more dangerous or sinister sleep disorders such as narcolepsy.”
This is an overpowering need to sleep caused by a problem with the brain’s ability to regulate sleep. Patients may have sleep attacks where they fall asleep suddenly or have difficulty staying awake for long periods in the day even when they have slept adequately at night.
For most patients, Dr Chong has this advice: “Start by making sure you get enough sleep. Do what you can to relieve stress in your life, especially just before bedtime.”
“Sleep paralysis is something normal and physiological so there is no specific medication for it. But treatment starts with identifying and treating the possible predisposing factors, such as excessive alcohol consumption or a very stressful lifestyle.”
DR CHONG YAW KIAN, an ENT consultant who runs the Sleep Clinic at Tan Tock Seng Hospital
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