This is usually caused by several factors.
- Use of non-brand named bulbs.
- Larger wattage bulbs, which cause excessive heat build-up shorting the life of the bulb.
- Power Surges.
- Bad light bulbs
- The bulb is screwed in too tight
- Too much vibration
- Turning off and on too often
- Loose or improperly connected fixtures or wiring
Check that your bulb socket is providing good contact to the center of the bulb. You may have to clean and/or lift up the center contact (while the power is OFF)