Recessed light fixtures can be a major source of heat loss, but you need to be careful how close you place insulation next to a fixture unless it is marked. "I.C."—designed for direct insulation contact. Check your local building codes for recommendations.
When lighting a sloped wall or a tight space, consider fiber optics. Light from a projector travels through fiber optic strands to a glass brick or other fixture. One line voltage lamp can operate up to 20 glass bricks as bounce light or accents lights. In a mural, individual fiber optic strands create stars for dramatic effect.