Want a good night’s sleep? Be positive – consistently. Although happiness is generally good for sleeping, when a person’s happiness varies a lot in reaction to daily ups and downs, sleep suffers, reports a Cornell study published online in the Annals of Behavioral Medicine.

The researchers analyzed data from 100 middle-aged participants in a longitudinal study of midlife in the United States that included telephone interviews about participants’ daily experience as well as subjective and objective measures of sleeping habits. The study looked at the overall levels of positive emotion that the participants experienced in their lives – those associated with more stable personality traits, as well as daily fluctuations in positive emotions in reaction to daily events.

The team found that, as expected, having a more positive general outlook on life was associated with improved sleep quality. However, they found that the more reactive or fragile a participant’s positive emotions were in relation to external events, the more their sleep was impaired, especially for individuals high in positivity to begin with.

“Previous research suggests that the experience of joy and happiness may slow down the effects of aging by fortifying health-enhancing behaviors such as restorative sleep,” said first author Anthony Ong, associate professor of human development in the College of Human Ecology. “Our study extends this research by showing that whereas possessing relatively stable high levels of positive emotion may be conducive to improved sleep, unstable highly positive feelings may be associated with poor sleep because such emotions are subject to the vicissitudes of daily influences.” Ong added, “These findings are novel because they point to the complex dynamics associated with fragile happiness and sleep that until now have been largely attributed to unhappy people.”

Ong co-authored the study, “Linking stable and dynamic features of positive affect to sleep,” with Deinera Exner-Cortens and Catherine Riffin, Cornell graduate students; Andrew Steptoe, University of London; Alex Zautra, Arizona State University; and David Almeida, Penn State University.

The research was funded in part by the National Institutes of Health and the Canadian Institutes of Health Research.

Karene Booker is an extension support specialist in the Department of Human Development.