Scientists believe the position in which a person goes to sleep provides an important clue about the kind of person they are.
Professor Chris Idzikowski, director of the Sleep Assessment and Advisory Service, has analyzed six common sleeping positions - and found that each is linked to a particular personality type.
Those who curl up in the foetus position are described as tough on the outside but sensitive at heart. They may be shy when they first meet somebody, but soon relax. This is the most common sleeping position, adopted by 41% of the 1,000 people who took part in the survey. More than twice as many women as men tend to adopt this position.
Lying on your side with both arms down by your side. These sleepers are easy going, social people who like being part of the in-crowd, and who are trusting of strangers. However, they may be gullible.
People who sleep on their side with both arms out in front are said to have an open nature, but can be suspicious, cynical. They are slow to make up their minds, but once they have taken a decision, they are unlikely ever to change it.
Lying on your back with both arms pinned to your sides. People who sleep in this position are generally quiet and reserved. They don't like a fuss, but set themselves and others high standards.
Lying on your front with your hands around the pillow, and your head turned to one side. Often gregarious and brash people, but can be nervy and thin-skinned underneath, and don't like criticism, or extreme situations.
Lying on your back with both arms up around the pillow. These sleepers make good friends because they are always ready to listen to others, and offer help when needed. They generally don't like to be the centre of attention.