Stretching after sleep helps to realign muscles and sends a signal to the brain that it's time to start using the muscles again. Blood flow decreases in muscles in a state of relaxation, and stretching upon waking increases the blood flow to muscles.
People often lie in the same position for an extended period of time while sleeping. This causes muscles to become stiff due to a lack of movement. The body is naturally warm after sleeping, which is effective for stretching to get muscles loose, iron out the kinks and get them ready to start the day. The heart rate is slow while sleeping, and stretching increases the heart rate.
Stretching the muscles as the heart rate rises increases the blood flow into muscles after a period of stability. This increased blood flow helps with flexibility. Proper flexibility of the muscles increases balance and posture to minimize the risk of strains and injuries. Better flexibility also increases vitality and endurance in the body.
Stretching helps to relieve tension and stress in the body and muscles. To get the maximum effectiveness from stretching, make stretches long and slow, rather than making them quick and holding them. The natural motion of stretching provides the body with numerous benefits.