1 The foetus

On your side, legs bent  

2 The soldier

On your back, legs straight, arms by your side

3 The starfish

On your back, arms and legs outstretched

4 The log

On your side, arms straight down

5 The freefaller

On your front, head turned, arms up on the pillow

6 The yearner

Sleeping on one side, arms reaching out

via telegraph