I felt pretty good when I got up and my wakeup HR was 49, but when I started to run I could tell I was tired. I ran a slow pace from 11:30 to 12:00 for 3 1/2 miles. It felt hot to me, even though the temperature was in the low to mid 80s (F).
I can think of two reasons why I was tired. First, I had good runs on Saturday and yesterday, and I needed a rest day. Second, my wife and I attend a family reunion last night, and I was on my feet for over three hours, including a mile walk around a pond. The good news is that I've been sleeping well.