Proper and restful sleep may be the foundation of our ability to understand complex emotions, according to research that came out of the annual scientific meeting of the Associated Professional Sleep Societies last week.

"Sleep essentially is resetting the magnetic north of your emotional compass," said Matthew Walker, director of the Sleep and Neuroimaging Lab at the University of California, Berkeley. Walker and colleagues analyzed 36 adults who were asked to interpret the facial expressions of people in photographs after being allowed to nap or not nap during the day. Those who achieved REM sleep, which is when dreaming normally happens, were better able to identify expressions of positive emotions such as happiness in other people. People who didn't dream were better at spotting negative emotion.

Walker told Time magazine that this may reflect evolution, if you are tired and can only pay attention to one thing, it is better to look out for things that might hurt you.

Careers in psychology can lead to studying major factors underlying our mental makeup, such as sleep. The American Academy of Sleep Medicine has more than 7,000 clinicians, researchers and other health-care providers in the field of sleep medicine.