You feel good about life and yourself. This is an open position that shows confidence and relaxation. You're open to new people, experiences and situations. Beware though, if your arms and legs are widespread when you sleep.. your confidence may be getting out of hand and leading to arrogance.
You're the type of person that likes to take charge and make every decision on your own. You pay very close attention to detail and want to achieve your goals. Sleeping on your stomach may also indicate that you are stubborn and believe that you're always right.
Sleeping in the fetal position
This may indicate that you are vulnerable or insecure. This is the position babies are in the womb, so if you revert back to this sleeping position, you may feel the need for someone to take care of you. This position may also mean that you are intimidate by life right now and are not up for new challenges.
This usually means you're very adaptable. This seems close to the fetal position, but you're not tightly balled up. You're usually very relaxed and able to take on a lot of challenges in life. You're stable and reliable and mentally balanced.
Go more in depth with your sleeping position here: