Dr Lad made an interesting note "Mudras can specifically mean facial expression." He then goes on to describe the dance of Kathak and other traditional Indian dance where the storyteller colours in the story via expressing humility, love, compassion, happiness, joy, sorrow, anger, fear and frustration in his face.
Isn't this wonderful?
We get used to body yoga and hand mudra and singing yoga and philosophy yoga but rarely do we talk about face yoga! Ha!
Our eyes can observe the other parts of our body and the idea is, if the body is well then it reflects in the face.
But what if, every morning when we meditated, we did face yoga - closed our eyes and simply observed each part of the facial tension falling away. Breathe in, relaxed the jaw and exhaled. Breathe in, relaxed the lips and exhaled.
And so on. Until you felt like your face reflected a state of peace you want to begin the day with.