What Could Small Cluster Of Dark Bruises On Arms Indicate?

I woke up this morning and noticed that I have a small cluster of tiny dark bruises on my arm. They are on the "flappy" part of my arm. This is not my first time waking up with this. About a year or so ago I had the same thing on my leg., right above my knee cap. I believe i had it again a few months ago, but the bruises were not as dark that time. I do have the tendency to wake up with random bruises often, but these ones strike me as "not normal."