Sleepy! Early symptom?

Kelli • Ttc #1
I have a busy life, and always get a good bit of exercise. For the last 2 days I have been exhausted, I never nap but yesterday after I walked the dogs, lay down and woke up 15 hours later.  So not like me, I'm still tired. I'm only 5 dpo but could this be a symptom?  I don't want to get my hopes up but we have been ttc for over 2 years.  Any else have the same?  Zzz