Key design principles for small bedroom calm include restraint, rhythm, and repetition to create visual harmony. Limit furniture to essentials and stick to a minimalist layout to reduce clutter and overwhelm. Repeat colors and materials across surfaces to provide a rhythmic flow that soothes the eye. Incorporate soft layers like rugs, cushions, and curtains in warm neutrals or calming hues to add texture without chaos. Prioritize intentional lighting and built-in storage to maximize space while maintaining serenity. These principles turn compact rooms into restful retreats.