Sarah, we have had the same thing in our house last week. My kids woke up fine, Lily even ate some toast and milk before she threw it up everywhere! For her it was about 15hrs she was sick, for Liam it was about 6ish hours, then all of a sudden they were fine! There was no fever or other symptoms of being sick. I took Lily to the doc and he said it was just a viral thing. Keep her hydrated and get her to rest. That's it! Hope your LO's are better soon, it's horrible when they're sick