There is a purpose to the darkness. Deep relaxation at the end of a yoga session helps us to regulate our breathing and enjoy the benefits of all the poses we just did. In addition, we learn to observe our body and breathing and be aware of any imbalances in our bodies.
Additional benefits for mothers-to-be in our prenatal yoga classes are learning an abilty to unwind upon demand and need for rest.
So let go and enjoy that few minutes of darkness after class!