Lighting systems for use in building interiors, for example, which include a plurality of light modules each having an elongate substrate with a lower surface, and electrical circuitry including a plurality of LED units printed to the lower surface via thick film techniques. Each light module is formed as a single-component, packaged construct for easy installation, and facilitates conductive transfer of heat away from the LEDs for enhanced power efficiency. The light modules may be releasably connected to, and extend from, an elongate spine unit which provides structural support and power input to the light modules and optionally, the system may employ use of metallic components, such as the metallic substrate of a light module, for directly conducting current to power the LED units.