Sleep researcher Chris Idzikowski has studied the sleep positions of thousands of people and has found that certain positions tend to correlate with certain personality characteristics. For instance:

Fetus position (curled up in a ball): Tough on the outside, but sensitive on the inside

Log (on the side, with arms and legs at side): Trusting and easy-going; like being in the in-crowed

Yearner (on the side, with arms down and legs stretched out): Suspicious; slow to make up mind, but determined

Soldier (on the back with arms to the side): Quiet and reserved; set high standards

Freefall (flat on the stomach with arms around pillow): Brash and loud, but thin-skinned; sensitive on the inside

Starfish (on the back with arms and legs stretched out): Sensitive to others' needs; good friend; don't like being centre of attention