Lighting levels similar to those that are comfortable for watching TV are appropriate. This will help increase the apparent contrast and reveal more shadow details in your images. A monitor hood (included with many high-end models) may be helpful here.
When measuring your screen for calibration and profiling, do switch the lights off, draw blinds or curtains, etc, to minimise the chance of stray light getting into the measuring instrument and giving false readings. Once everything’s set, go ahead and run your calibration and profiling software and enjoy the benefits of accurate color.