From keeping up a daily exercise routine to eating healthy foods and avoiding impulse purchases, self-control is hard work. Ironically, when it comes to making decisions about our bodies, a new study in the Journal of Consumer Research finds we make better health care decisions when we're feeling tired and run down.

"We proposed that people are more motivated to engage in healthful behavior when they are depleted and perceive their safety to be at stake," write authors Monika Lisjak (Erasmus University) and Angela Y. Lee (Kellogg School of Management, Northwestern University).

Across five experiments, the researchers looked at how consumers use what they term "self-protective motivation" when it comes to avoiding danger. They also studied consumer preference for products that emphasize safety.

In one study, participants were asked to read a health message that both described the dangers of kidney disease and advocated the benefit of early detection. The risks associated with a family history of kidney disease were also highlighted in the message. The authors found that for people with a family history of kidney disease, those who were feeling depleted exhibited a higher likelihood of being tested than those who were feeling healthy. Participants without a family history of kidney disease expressed a similar low interest in being tested regardless of how they were feeling.

In a second study looking at product selection, participants were asked to fill out a survey on health and fitness habits either before or after working out at the gym. As a thank you gift, the participants were able to choose either sunblock or moisturizer. When participants were surveyed after working out, the likelihood of choosing sunblock was much greater than choosing the moisturizer.

"Consumers value products that emphasize safety features more when they are feeling depleted. Retailers may benefit from placing safety-related products near the checkout or running ads for security-related products at the end of the day," the authors conclude.