title: Loneliness and health: potential mechanisms.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Psychology, University of Chicago, Chicago, IL 60637, USA. cacioppo@uchicago.edu
authors.forename: John T
authors.initials: JT
authors.lastname: Cacioppo
authors.forename: Louise C
authors.initials: LC
authors.lastname: Hawkley
authors.forename: L Elizabeth
authors.initials: LE
authors.lastname: Crawford
authors.forename: John M
authors.initials: JM
authors.lastname: Ernst
authors.forename: Mary H
authors.initials: MH
authors.lastname: Burleson
authors.forename: Ray B
authors.initials: RB
authors.lastname: Kowalewski
authors.forename: William B
authors.initials: WB
authors.lastname: Malarkey
authors.forename: Eve
authors.initials: E
authors.lastname: Van Cauter
authors.forename: Gary G
authors.initials: GG
authors.lastname: Berntson
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001143:Arousal / Q000502:physiology; D001341:Autonomic Nervous System / Q000503:physiopathology; D001794:Blood Pressure / Q000502:physiology; D005260:Female; D015577:Geriatric Assessment; D015438:Health Behavior; D006304:Health Status; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D008132:Loneliness / Q000523:psychology*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012890:Sleep / Q000502:physiology; D013001:Somatoform Disorders / Q000503:physiopathology / Q000523:psychology*; D013334:Students / Q000523:psychology
chemical_list: D006854:Hydrocortisone