"We found that sleep, mood, and stress are all important factors in determining a sense of control, and in whether older adults feel they can do the things they want to do," said study co-author Shevaun Neupert. She is a professor of psychology at North Carolina State University.
"This finding is important because when older adults begin to lose their sense of autonomy, it can lead to changes in behavior that adversely affect their health and well-being," Neupert explained in a university news release.
The findings could help guide efforts to improve people's sense of control, the researchers suggested.
For the study, the investigators analyzed data on 205 people, aged 60 to 94, who provided information on a wide range of psychological variables on eight days over a three-week period.
The researchers wanted to determine which, if any, of those variables, affected two "control" beliefs: a person's sense that he or she can do the things they want to do; and the sense that they are in control of their own lives.
Several of the variables had a significant effect on both beliefs, the study authors reported.
"We know there are things people can do to improve their mood and to improve their sleep. And while sleep and mood are things most people think are important, this study highlights a very specific reason that they are important," Neupert added.
"When people think they have little or no control in their lives, they may stop doing some of the everyday things that are important for self-care -- because they believe those things don't matter," she said.
According to study first author Shenghao Zhang, the researchers also found that "being in a good mood made people feel better about their competence and control while being in a bad mood made people feel worse about those things." Zhang is a Ph.D. student at North Carolina State University.
"Lastly, we found that stressful events on one day had an adverse effect on an individual's subsequent control beliefs. These results suggest that the adverse effect of stressful events can last for more than a day," Zhang said. "It would be interesting to conduct additional work to determine how long the effects of stress resonate in regard to control beliefs."