One in 50 people experience sleep paralysis at least once a month, according to research published in the latest issue of the magazine Neurology.
The condition is characterised by the inability to move or speak for several minutes after waking up and can be caused by disrupted sleep patterns, stress or prescription drugs.
"When you dream, your body becomes actively paralysed so that you don't carry out the movements in your dreams. Sleep paralysis occurs when this continues into waking consciousness," said Dr Chris Idzikowski, the chairman of the Royal Society of Medicine's forum on sleep and its disorders.
The study, of 8,100 people, showed that people who experienced sleep paralysis often felt sleepy during the day and had difficulty falling asleep at night. One in eight peopleexperienced their first episode during childhood.
"People experiencing sleep paralysis on a regular basis should seek medical attention," said Dr Maurice Ohayon, of New York University, who conducted the study.
"In most cases, sleep paralysis can be treated. Contrary to previous findings that sleep paralysis began in adolescence, our research showed it can start at any age."
Around 6 per cent of those who took part in the study had experienced sleep paralysis at least once in their lifetime.
"It used to be called `night nurses' paralysis' because of the association with shift work," said Dr Susan Blackmore a senior lecturer in psychology at the University of the West of England, who is heading the first major academic research into sleep paralysis in Britain.
"We have got to be paralysed for dreaming, but there are mechanisms to make sure we don't realise this," she said.
According to Dr Blackmore, it is a natural human condition which does not require treatment and should be treated by learning relaxing techniques.
Preliminary findings from a survey of 420 people being conducted by Dr Blackmore's team showed that 6.8 per cent suffered from the condition at least once a month, and 43 per cent had experienced it at some time.Reuse content