The answer to 'why is my recessed lighting dimming lights' is that there are several common causes, including faulty dimmer switches, loose connections, or overloaded circuits. Dimming lights can also be a symptom of more serious electrical issues.
One of the most common causes is a faulty dimmer switch. Dimmer switches wear out over time, and if they're not working properly, it can cause your recessed lights to dim or flicker. You may be able to replace the dimmer switch yourself, but if you're not comfortable working with electrical wiring, it's best to call a professional electrician.