STUDY: When we're stressed, we default to good and bad habits

There's a common notion that the more tired and stressed people get, the more likely they are to fall back on bad habits, such as  overeating or drinking too much. But a new study from researchers at USC and UCLA finds we're likely to default to learned habits — of either variety.

"Both good and bad habits are automatic responses," said Wendy Wood, a professor of psychology at USC and co-author of the study. "They're brought to mind when you're in a given context and you can decide not to do them, but if you don't have much willpower and you're feeling stressed, it's hard to make those decisions, so we tend to repeat our old habits." 

Wood co-authored the study on stress and habits with social psychologist David Neal, along with Aimee Drolet, a psychologist at UCLA who studies consumer decision-making. 

Wood said one of their five experiments noted what 65 UCLA students ate for breakfast during an average week compared to an exam week. For example, if a student had a habit of eating pastries, then they would be more likely to eat pastries during an exam week.

"They're focusing on studying, they're not focusing on what they're eating. They don't have much energy leftover for that," Wood said. "But that was also true for people who ate oatmeal. They were more likely to eat oatmeal during exam weeks than during non-exam weeks." 

Wood said her favorite example of this theory is highlighted in the bicycle rides she used to take with a friend who was a professional cyclist. They would ride bikes on the cyclist's day off, when she was supposed to be resting. They would ride really slow together. At the beginning of the ride, the professional cyclist would find it easy to go slow , but toward the end she would speed up.

"She would get really tired and mentally keep thinking, 'Go slow, go slow,' and would find herself speeding up to her normal pace," Wood said. "That's really the phenomenon — when you're tried, you fall back on doing whatever is you typically do, even if it's going super fast speeds on a bicycle. "

Wood said the study's findings show the importance of maintaining healthy behaviors every day —  such as exercising and eating properly —  so that you'll default to good choices when you're stressed and unable to make decisions.

The full study hasn't been released yet, but  is set to appear in the  June issue of the Journal of Personality and Social Psychology, published by the American Psychological Association.