In Ashtanga Yoga, it has always been a tradition to take to rest from asana practice on the days of the new moon, known as amavasya, and the full moon, known as purnima. The reason for this is that on these days, the gravitational forces of the sun and moon are greater and have a more pronounced effect on the planets. One observable effect of the sun and moon’s gravitational pull on the earth is that the ocean’s tides are higher and lower on these days. Their relative positions also create different energetic experiences. During the new moon, students can sense a heaviness and feel too tired to practice. During the full moon, the energy can often be frenetic and students are thought to be more prone to injury. Allowing extra rest on these days is therefore important for regeneration. Practicing Ashtanga Yoga over time makes us tune into the natural cycles of our bodies and our environment. Observing moon days keeps us in touch with these cycles of nature and brings us into greater harmony with it.