Motion Sensors too sensitive?

I have had my ST hub and sensors for about six months. I have one motion sensor in use at this time. At first it was working fine and then it seemed to have lost its connection to the hub. Did a reset, replaced the battery and then it seem to work fine for several months. Lately it seems to be too sensitive. It detects motion as it should but it also is sending extraneous signals with no motion. It sends a signal then 2 for 3 seconds later sends another notification. I thought it might be picking up light changes from passing cars, sunlight or some other source, since I knew there was no motion in the area of the sensor. As a last resort I took the sensor down and placed it in a dark drawer to eliminate any stray light source. I has not sent any false signals since that time. It serves not useful function in the drawer. Any known solutions . Thanks in advance.