If you're a driver who has been noticing that your car's headlights don't seem to be as strong as before, you know that the bulb might be on the way toward burning out. But another possible culprit is the headlights' direction. A perfectly strong headlight can seem dim if it's aiming away from its usual spot. While you'd think headlight aim would be something that wouldn't change unless forced to, it can really change for a number of reasons. Here are three common ones that you should look out for.

Heavy Loads in the Trunk

If you tend to load a lot of heavy stuff into your trunk, that can make the back of the car dip due to the weight, of course. But that dip also means the front of the car is rising up a bit as well, like a seesaw. If the stuff in the trunk is heavier than you are, then you sitting in the driver's seat won't completely offset the weight in back. The resulting rise makes the headlights aim a little too high. Try to distribute weight throughout the car more evenly.

Aging Connections

Like other connections in the car, age can cause the connections and brackets holding the headlights in place to slowly loosen. The resulting looseness lets the headlights gradually drop down or otherwise go out of kilter. Whenever you bring your car in for service at your mechanic's shop, or whenever you work on your car, test the aim of the headlights by shining them against a wall where you know where the lights are supposed to land. If you see the lights are uneven or shining in a different spot, you can have your mechanic inspect the connections and tighten any loose ones.

Impacts -- of Any Strength

It's a given that an accident involving the car might cause the headlights to jump out of alignment, but really, any repeated impact can hasten the gradual loss of aim, including constantly closing the hood of the car (remember, to close that, you usually have to let the hood drop down with a mini-slam). As with aging connections, periodic inspections to see if these impacts are causing an issue are warranted.

If you're really having problems keeping the headlight patterns correct, though, you may want to talk to repair techs who specialize in headlights or the electrical system of the car. You could have a faulty connection that is not supporting the headlight as it should.