Door bell detects motion no one there

So my doorbell keeps detecting motion when no one is there. The other morning at 12:50 am it started going off and kept doing it until like 1:30 am. The thing is in that time I was actually sitting on my phone looking at "LIVE VIEW" and the motion detected goes off. Now I am looking outside my door live. There was no car, there was no cat, or raccoon...so it can't be that it is picking up motion like a car, because like I said I was looking at it live. This happens here and there all the time. Just now, I am at work and the alarm goes off on my phone, I look nothing there...and once again, I am looking at the phone LIVE and it shows motion but nothing is there. No car, No person. I noticed a lot of people are saying the same thing....I am not sure how many people are looking at it live to see that there wasn't a car or any motion in the distance...because it seems that is the explanation that it is picking up other things...but I am not sure what the answer is when your looking at it live and there wasn't a car or anything to trigger it. So unless there are more spirits walking amoung us and no one has known in the past because people haven't had as many rings as they have now and are very popular, these spirits are being picked up...LOL...if you don't believe in that then something is wrong with their technology and I need to find out what it is because I don't want to sit up for 45 minutes at 1:00 in the morning when I have to go to work listening to my ring go off afraid someone is coming up to my door and look and nothing is there. I don't want to be at work and here my phone go off and I am thinking someone is at my door who doesn't suppose to be there because I haven't ordered anything. Is there a answer for this?