It is very common for those of us getting radiation treatments to experience fatigue. In fact, it is considered to be the most common side effect after redness of the skin. I became very well acquainted with fatigue near the end of my first 6 chemo treatments and during nearly all of my last 4 rounds.
My first inclination that I'm starting to experience radiation related fatigue is that I started saying, "I'm tired" a few days ago. I've also taken a couple mid-day naps this week. Then, there's the waking up before my alarm in the morning and being unable to go back to sleep, but also feeling unable to really move.
However, the biggest indicator has to have been today, as evidenced by the prolific number of posts I've had on facebook. When I haven't been in the car, at radiation, or walking at the community center, I'm right back in my recliner. I'd have the TV on, but I'm too tired to either get up and turn it on or find the remote. But hey, all three boys are home...one of them can do that for me.