There are many reasons why lights dim.
One cause might be that the lights are on a circuit with a larger appliance such as a refrigerator or air conditioner.
There might be a corroded, broken or loose neutral wire which causes the lights to get brighter and dimmer.
Frayed wiring or loose connections could also cause lights to dim.
If you notice your lights are dimming, you need to find the source of the problem. It could be the light bulb itself or it could be something more serious.
Observe appliances when they are first turned on and then while they are running.
Professional, licensed and insured electricians have more ways of searching for electrical problems and will be able to accurately troubleshoot the wiring and circuitry in your home. Once the problem is discovered, an electrician will be able to quickly make a correction.