Oh, here's where I come across as a lunatic ...
I have a noisemaker. It plays a variety of sounds continuously all night: rain, waterfall, ocean, Amazon rainforest, staticky white noise, traffic, even a heartbeat (which kinda creeps me out, but I guess would be soothing for babies). I put it on the "rain" setting and leave it on all night. I cannot sleep without it, and pack it when I travel. (I even leave it on when it's actually raining.
I also require perfect darkness. We have blinds and heavy curtains in our bedroom, and heavy curtains in the hallway outside. No nightlights for me! (I should point out, though, that I require very little light to see by, so even a small amount of light seems very, very bright to me.) I've considered getting a sleeping mask, but I think my hair would get tangled in the strap.
I could go into the other bizarre things I require while I sleep (certain number of pillows, certain heaviness to the blankets, etc.), but I'm sure you all already think I'm crazy enough!