This is a scanning technique that I have used myself for years. It has become my bedtime ritual. It is a useful grounding exercise as it brings awareness back into balance. Not only does the body scan help to clear away a cluttered mind, it is also an excellent tool in identifying physical stresses and upsets.
Pain can be so overwhelming in one part of the body that other imbalances of the body get neglected. The body scan is an exercise in assembling the larger hurts alongside the minutest details of stresses that you may have otherwise been overlooked.