Radiation = sleepiness.

Daddy- Well Radiation is once again kicking your butt. It always take all your energy. You are so sleepy, you fall asleep anywhere. I can't wait for you to be done with this round of radiation. Today is day 7. So about half way there. You are so worried you won't be able to stay awake and watch the super bowl. I Love you Daddy and you are so brave.