Calms the brain
Helps to relieve stress and mild depression
Relaxes the body
Reduces headache, fatigue and insomnia
Helps to lower blood pressure
*In case of pregnancy, head and chest should be raised on a bolster. In case of back injury or discomfort, bend the knees and support with a bolster.
Savasana should be done at the conclusion of every practice.
While it looks like you're just "laying there", it is still important to think about alingment in Corpse Pose. Your body should be in a neutral position. Check to make sure your legs are even relative to your midline, that your ears are even in relation to your shoulders, that your shoulder blades are resting evenly on the floor. Lengthen the spine, broaden the shoulders, spread the collarbones.
Think about softening everything. Let the back of the hands rest on the floor. Let the feet turn our slightly. Soften the body. Soften the face - the tongue and the nose and the eyebrows. Close the eyes.
I practice savasana for 5 minutes of every 30 minutes of Asana. So, for an hour long practice I do 10 minutes of Savasana. And, on days when I really don't feel like doing yoga, I just do Savasana. There is great benefit to making the time for yourself, becoming still, and quietening the mind.