Two studies using cross-sectional designs explored four possible mechanisms by which loneliness may have deleterious effects on health: health behaviors, cardiovascular activation, cortisol levels, and sleep.
In Study 1, we assessed autonomic activity, salivary cortisol levels, sleep quality, and health behaviors in 89 undergraduate students selected based on pretests to be among the top or bottom quintile in feelings of loneliness. In Study 2, we assessed blood pressure, heart rate, salivary cortisol levels, sleep quality, and health behaviors in 25 older adults whose loneliness was assessed at the time of testing at their residence.
Total peripheral resistance was higher in lonely than nonlonely participants, whereas cardiac contractility, heart rate, and cardiac output were higher in nonlonely than lonely participants. Lonely individuals also reported poorer sleep than nonlonely individuals. Study 2 indicated greater age-related increases in blood pressure and poorer sleep quality in lonely than nonlonely older adults. Mean salivary cortisol levels and health behaviors did not differ between groups in either study.
Results point to two potentially orthogonal predisease mechanisms that warrant special attention: cardiovascular activation and sleep dysfunction. Health behavior and cortisol regulation, however, may require more sensitive measures and large sample sizes to discern their roles in loneliness and health.
From the Department of Psychology, University of Chicago, Chicago, IL (J.T.C., E.C.); the Department of Psychology, Ohio State University, Columbus, OH (L.C.H., R.B.K., G.G.B.); the Department of Psychology, Illinois Wesleyan University, Bloomington, IL (J.M.E.); the Department of Social and Behavioral Sciences, Arizona State University West, Phoenix, AZ (M.H.B.); the Department of Medicine, Ohio State University School of Medicine, Columbus, OH (W.B.M.); and the Department of Medicine, University of Chicago, Chicago, IL (E.V.C.).
Address reprint requests to: John T. Cacioppo, University of Chicago, Department of Psychology, 5848 S. Maryland Avenue, Chicago, IL 60637. Email: firstname.lastname@example.org
Received for publication July 12, 2000; revision received June 27, 2001.