Smart lighting research traditionally focuses on conventional incandescent and fluorescent luminaries. However, in addition to its higher energy efficiency and longer lifetime, Solid State Lighting (SSL) offers better control of spectral, spatial, temporal polarization, and color properties of light. Combined with the recent developments in smart environments research, SSL utilizing Light Emitting Diodes (LED) creates a new playground for user-light interaction. We present a novel illumination model for SSL and implement this model on a wireless sensor network (WSN). The light sensors and actuators in the WSN provide services for sensing illumination changes and dynamically adjusting luminary brightness according to user preferences. Experiments conducted two key scenarios, i.e. reading and watching TV, show that the preferred illumination levels in an activity space can be achieved and maintained, irrespective of external light variations.