45 min before both sunset and sunrise
It is recommended to turn your headlights on 30 minutes after sunset and keep them on until 30 minutes before sunrise for optimal visibility and safety when driving in low-light conditions. This ensures that you can see the road clearly and other drivers can see your vehicle.
Headlights are required to be turned on in Tennessee 30 minutes after sunset to 30 minutes before sunrise, when visibility it low, and in adverse weather conditions.
Where I live it is 30 minutes before sunset and 30 minutes before sunrise that you are supposed to have your headlights turned on.
30 minutes before sunset
It will depend on the motor vehicl;e laws of your particular jurisdiction. In some places it is only 1/2 hour before, and after, sunset and sunrise.
30 Minutes before sunset
the sun is visible to us about 2 minutes before the sunrise & about 2 minutes after actual sunset because of atmospheric refraction.By actual sunrise, we mean the actual crossing of the horizon by the sun. The time difference between actual sunset & the apparent sunset is about 2 minutes. The apparent flattening of the sun"s disc at sunrise & sunset is also due to the same phenomenon .
Headlights are used during times in which it may be hard to see. In most states, headlights must be used when driving from dusk before sunset to sunrise.
30 minutes before sunset and 30 minutes after sunrise and in reduced visibility
From sunrise to sunset is about nine hours and about fifteen minutes. This doesn't include the twilight before sunrise or after sunset (about thirty minutes or so on each end).
Thirty minutes before sunrise to sunset
Headlights should be on at least 30 minutes after sunset and can be off 30 minutes before sunrise. They should also be on during times of limited visibility, such as in rain or when it is snowing.
Most states require you to turn on your headlights a half an hour (30 minutes) BEFORE sunset. (That is based on my experience, driving mostly in the Northeast.)