February 15th, 2015
(written by lawrence krubner, however indented passages are often quotes). You can contact lawrence at: firstname.lastname@example.org
I sometimes get sleep paralysis, so I find this surprising. Neither of my parents had sleep paralysis, so I wonder how far back it goes?
Sleep paralysis often occurs during the rapid eye movement (REM) stage of sleep, when people are usually dreaming. In REM, the muscles are nearly paralyzed — possibly to prevent people from acting out their dreams, scientists say. Some people who suffer from sleep paralysis experience hallucinations of a terrifying figure pressing down on them and preventing them from moving.
Estimates of how many people experience the phenomenon vary widely. Some studies have found that just over 7 percent of people will experience the feeling at some point in their lives, whereas other studies suggest as many as 60 percent of people will.
“It’s more common than you would actually expect,” Denis told live Science. Yet scientists don’t really know what causes the phenomenon, or whether it is heritable.
To find out, Denis and his colleagues used data from 862 twins (identical and nonidentical) and other (non-twin) siblings between ages 22 and 32 in England and Wales. The participants indicated on the survey whether they agreed with the statement, “Sometimes, when falling asleep or waking up from sleep, I experience a brief period during which I feel I am unable to move, even though I think I am awake and conscious of my surroundings.” [Sleep Paralysis: Spooky Art Images]
By comparing the responses of identical twins, who share almost all of their DNA, with those of nonidentical twins or siblings, who share about half of their DNA, the researchers found that genes accounted for more than 50 percent of the incidence of sleep paralysis.
They also found that sleep paralysis was more common in people with anxiety, those who weren’t getting good sleep and those who had had traumatic experiences, such as an illness or death in the family.