Embodiments of the present invention provide a distributed computer system and a method for determining the quality of sleep of a sleeping user. The distributed computer system will determine the quality of sleep by detecting the changes in body posture of the sleeping user. The quality of sleep will be determined by the feature vectors associated with each posture of the sleeping user. The posture of the user will be determined by recording a body motion signal caused by the mechanical and muscle movement of the body of the user.