According to an article on WashingtonPost.com:
"Beyond leaving people bleary-eyed, clutching a Starbucks cup and dozing
off at afternoon meetings, failing to get enough sleep or sleeping at
odd hours heightens the risk for a variety of major illnesses,
including cancer, heart disease, diabetes and obesity, recent studies
You can read the full article here
In my own experience, I have seen a tremendous correlation between lack of sleep and increased UC symptoms.