That's your fatigued adrenals talking - they might need more support.Check out teh adrenal forum here!
You could also put yourself unduly under stress without knowing it. One of my issues was always trying too hard and feeling guilty if I did not get everything done.
While having a bodywork session with a very gifted intuitively bodyworker it came out that I was trying so hard because I was still seeking approval from my mom.
My mom was not very present in my life when I was little and I spent a lot of time with an elderly lady who had rented an appartment in my parent's house. I had always known I seemed to be more independent and did not have a very close relationship to both my parents, but I had no idea that it was still affecting me this much and why this actually was.
You may be dealing with similar issues that are putting more stress on you !