Small tremors/vibrations

I've noticed for several months I am expericece a small vibration or tremor thoroughout my body when I waken or just before I fall asleep.  It isn't painful.  It is so barely noticeable that I wouldn't even notice it except that on occasion it seems to "stop" vibrating for a second.  That's when I notice it - when they start back up again.  They are just annoying.  It feels like I am on something that is vibrating (like laying in a car) and the vibration goes away when the gears shift, and then returns.  It stops momentarily about every 30 seconds for a couple of secons (though it has no set clock or time frame I can keep track of).   My husband doens't feel the vibrations so it's not apparent.  I am 43 and a female.