The short answer to the question "should I leave a light on for my cat while on vacation?" is generally no, you do not need to keep your home ablaze with artificial light 24/7, though a small nightlight or smart bulb can offer comfort during the pitch-black hours. While cats possess superior low-light vision compared to humans, they are not supernatural beings that can see in total, absolute darkness. Maintaining a consistent circadian rhythm is the thing is for their biological health. Let's be clear: leaving every light on for a week straight is more likely to stress your feline friend than help them navigate the living room.