I use an iOS8 app called Motion X 24/7 as an alarm. One feature I like is that it prompts you to measure your heart rate as soon as you wake up.This supposedly can tell you if you are overtraining or if you need extra time to recover.
Well, today my resting heart rate was 90!
Just to compare, my heart rate for the month of October has been fluctuating between 65 and 72. I guess I still haven't shaken off my Sunday run, where I ran a 10k and increased my pace every 2k from 8:30 to a maximum of 7:00. The workout had left me breathless, woozy, and I had thought I was going to pass out. Plus I wasn't able to get much sleep for 2 days. I was going to bed at 12:30 am and getting up at 5:30 am.
Because my heart rate was exceptionally high today, I decided to take a day off from running and get an extra few minutes of sleep. Maybe tomorrow I will be rested.
I also checked my log and found that my April average resting heart rate was 60, which tells me that my fitness levels has decreased, probably because I hadn't been putting in some serious mileage since August.