New research finds "significant associations" between a person's optimistic disposition and their sleep quality.
Sleep deprivation is a major public health concern.
In fact, around 30% of adults in the United States do not get the amount of sleep that is optimal for health.
Also, up to 70 million people in the U.S. have a sleep disorder.
A number of things can help improve sleep, such as getting a new mattress, limiting late evening alcohol consumption, exercising regularly, and strictly using the bedroom for rest.
New research suggests that there may be another ingredient that could help sleep, though it may be more difficult to obtain than a new mattress: an optimistic disposition.
The study, which appears in the journal Behavioral Medicine, finds that optimists tend to sleep better. This is a finding that builds on previous studies that have suggested that optimists have better cardiovascular health.
Dr. Rosalba Hernandez, an assistant professor at the University of Illinois at Urbana-Champaign School of Social Work, is the lead author of the new research.
Studying sleep and optimism
Dr. Hernandez and team examined 3,548 participants, ages 32–51, who took part in the Coronary Artery Risk Development in Young Adults (CARDIA) study.
The participants were non-Hispanic white and African American adults living in Birmingham, AL, Oakland, CA, Chicago, IL, and Minneapolis, MN, among other U.S. regions.
To assess the participants' optimism, the researchers asked them to express their agreement with a series of 10 statements using a five-point Likert scale, ranging from "strongly agree" to "strongly disagree."
Statements included positive ones (such as, "I'm always optimistic about my future") and negative ones (such as, "I hardly expect things to go my way"). The resulting survey score ranged from 6 to 30, with 30 being the most optimistic.
As part of the CARDIA study, the participants reported on the quality of their sleep twice, 5 years apart, mentioning the number of hours they slept regularly and any symptoms of insomnia.
Some participants also filled in the Pittsburgh Sleep Quality Index and the Epworth Sleepiness Scale, and they wore activity monitors that objectively measured how long they were sound asleep for and how restless they were during the night.
To assess the link between optimism and sleep quality, the researchers applied multivariate regression analyses.
Optimists 74% less likely to have insomnia
The study revealed that each increase in "standard deviation" — that is, the standard distance between two data points — correlated with a 78% increase in the odds of better sleep quality.
Participants with higher scores were also more likely to sleep for 6–9 hours each night and 74% less likely to have insomnia.
"Results from this study revealed significant associations between optimism and various characteristics of self-reported sleep after adjusting for a wide array of variables, including sociodemographic characteristics, health conditions, and depressive symptoms," says Dr. Hernandez.
"The lack of [healthful] sleep is a public health concern, as poor sleep quality is associated with multiple health problems, including higher risks of obesity, hypertension, and all cause mortality," she adds.
"Dispositional optimism — the belief that positive things will occur in the future — has emerged as a psychological asset of particular salience for disease free survival and superior health."
Dr. Rosalba Hernandez
Although the findings are purely observational, the study authors speculate on a possible mechanism that may explain them.
"Optimists are more likely to engage in active problem-focused coping and to interpret stressful events in more positive ways, reducing worry and ruminative thoughts when they're falling asleep and throughout their sleep cycle," concludes Dr. Hernandez.