It is possible to use a light dimmer to control light intensity.
Several lamps can be controlled by one dimmer. However you must not exceed the power rating.
The project will go easier if you start off by connecting only one detector circuit to only one dimmer. It will be increasingly difficult to hook up several detectors to a dimmer, and make them all cooperate.
The detector can be triggered by:
* timer
* flashlight
* interrupted light beam
* sound
* motion
* infra-red detection of warm body
Etc.
If you wish to control house current, then the detector circuitry must either be (a) isolated from house current, or (b) be compatible with direct connection to it.