I skipped class at uni today.
Oh no. Why did you need to skip class today?
I didn't feel like going to uni today.
We all need a break now and then, and it's not unreasonable to skip class once or twice. Just make sure that you're not making a habit of it, because if you miss too many class days then you'll start to fall behind. It's irresponsible to skip a lot of classes, especially when you're in university as you're training for your future profession.
It's fine. I was only going to sleep.
Uni definitely can be super stressful, and more props to you in trying to take care of your physical and mental health. Just try not to get used to it, because being a student is basically like a job. You can try asking your professor for lecture slides, or classmates for notes to catch up.