Night owls might think staying up late is a real hoot, but a new study hints that delayed sleep might have a sinister side. People who hit the sack late might have a greater risk of experiencing nightmares , according to scientists, although they add that follow-up research is needed to confirm the link.

"It's a very interesting preliminary study, and we desperately need more research in this area," says Jessica Payne, director of the Sleep, Stress and Memory Lab at the University of Notre Dame, commenting on the new findings.