While I am doing remarkably better with my UC symptoms, I've had at least a couple of days that exhaustion nearly overwhelmed me. But then my lifestyle has become pretty taxing, taking care of my 10 month old grandson full time plus doing my regular bookkeeping job from home.
I suspect that some of the exhaustion came from allergies, since its the season for high grass pollen and we've got cottonwood blowing around like crazy. Sometimes I think its easy to blame every symptom on UC (and my doctor does, too) and it may be something else going on.
But getting that rest is definitely essential.