Welcome. My name is ***** ***** would be glad to assist.
The light is controlled by a timing circuit which is turned on when the door is opened or closed.
This timing function activates a relay on the main board which then turns on the light.
It sounds like the circuitry is shorted in some respect, so that the timing is activated without the door being operated.
Not uncommon situation but less common than the light not working all together, which is the same failure, just the opposite direction.
There are only a couple options for the repair, either replace the main logic board or remove the bulb and use an alternate form of light activation. This is the same thing recommended when the relay and timing circuit fail and do not activate the light at all.
If you wish to use an alternate form, see the below links. The main board normally runs $65-$85 and can be found by posting the Model number of the opener.
Let me know anything further to be of more assistance,
Alternative garage light option
Motion Sensor Plug---CLICK HERE
Bulb Socket---CLICK HERE