I installed a motion sensor switch in my closet about 6 months ago. At the same time I replaced the light fixture. As of late the light has started turning on in the middle of the night. for several months it worked without a problem. I am perplexed why this motion sensor switch would start randomly turning on the light. The door is closed and the location of the closet is such that is not any wind or breezes that could cause something to move in the closet. I am wondering if that the use of LED bulbs could be an issue though that seems a bit odd.

Vibration, temperature and air movement can sometimes affect outdoor motion lights. Could any of these be a factor?

There is always the possibility "spooks" too.

likely the switch is getting triggered by RFI, radio frequency interference. very little is correctly isolated from outside interference. I'd put a snap-around ferrite choke (radio shack) around the leads as close to the switch as you can, and wrap.insulate it in place with good electrical tape like 33+.

ferrites can conduct electricity if they touch bare wires, thus the recommendation for tape.

Thank-you for the responses. I think the point of RFI interference is the issue. Adjacent to the switch I have a shelf where I have a wireless network switch and where I put my cell phone. I moved both of these about 5 feet away and the problem seems to have gone away. I am not sure which of the two wireless devices was causing the interference but the extra distance seems to have resolved the issue.

almost certainly it was the wireless network point.