PIR motion sensors don't have to be reserved for outdoor lights, they can be installed indoors too.
They are widely used in the commercial sector, but can also be used in the home. They are particularly suited to "pass-through" areas such as entranceways and hallways, where they will instantly turn on when you enter - then switch off after a set period of time.
There are a number of options available, including models that can be recessed into the ceiling, making them barely noticeable.
If you have lights that you want to be motion activated, feel free to get in touch today to discuss having PIR sensors installed.