Have you checked to see if the brights are not just burnt out? Rarely do they both go at the same time, but it is possible.
Problem with the charging system. Altenator, Battery, etc.. (may even be a loose belt causing the alternator not to spin fast enough to charge the battery).
according to Florida handsbook, you must dim your bright headlights within 300 feet of the vehicle ahead.
It is safe to use the bright [highbeam] headlights when there is no oncoming traffic/drivers who could be blinded by the bright light. Also, it is unsafe to use highbeams when there is fog or smoke which would reflect the light back to you, thus reducing the distance which you can see.
Headlights have two filaments, one for dim, one for bright. From your description it appears that one of the high beam filaments is burned out. Replace the bulb.
Low-beam headlights that are not property adjusted can make them as bright as high-bead headlights. They also can cause you to not see the full road ahead.
ldr sensor
It depends on what type of headlight you have. What auto do you have?
No
Because the lights are so bright
They need a better ground going to them. There not grounded good.
Switch? both headlights?
You've got a bad headlight switch and need to replace it, that's the switch you pull in the dash to turn the lights on. That's why the headlights only work on bright but not dim.