I've done it before... but apparently, it can be dangerous!

<< “Many appliances have fail-safe technology, like cutoff switches that are supposed to power down a dishwasher when it overheats,” Mr. Wolfson said. “But there have been incidents that cause concern in which consumers may need to take direct action themselves, like directly unplugging the appliance because of the experience of seeing smoke.”

There was a recent fatality involving a dishwasher left running overnight, he said, and it is not just heat-producing appliances that pose a threat. “There have been cases of cellphones sparking while left charging overnight,” he said.

The agency recommends operating appliances in the daytime, with supervision. Nighttime use, when energy demand is lower, “is fine, as long as someone is awake,” Mr. Wolfson said. >>

http://www.nytimes.com/2013/06/11/science/keeping-appliances-safe-overnight.html

Ah wow, I'll be more careful now! I had no idea this could happen...

Do you ever run your dishwasher or washing machine overnight while you're sleeping?