New moms, night owls, insomniacs, third-shift workers, and others who lose sleep on a regular basis already know that sleep loss can lead to a shorter fuse. Recently, scientists studied two groups of people -- one sleep deprived, one not -- using MRI and are now able to tell us why. The area of the brain that controls emotional responses becomes highly over-reactive when a person is sleep deprived, making it harder for that person to control emotions or put things into perspective.

Scientists think that this study may help mental health experts better understand the connection between psychiatric disorders and sleep. For the rest of us, it's just another reason to make getting enough zzzzz's a priority in our lives.