I hate my light

My bedroom light. Sometimes it takes a couple seconds and sometimes it takes two minutes but it's never instant. Usually it depends on the time of day. Later in the night it'll start taking longer and longer. I click the light switch and I stand in the dark. It. Is. So. Frustrating! I learned that if I wander around to the bed and click on the bed light (The bedpost has lights in it) then the overhead light turns on quicker, but man! I've never been in a room where I had to stand in the dark for 120 seconds or longer in order for the light to come on!