2.1 Participants

Participants (N=490) were drawn from the Adult Health and Behavior Project –Phase 2 (AHAB-II), a study of risk factors for heart disease in midlife adults. Our sample is derived from participants who completed all phases of the AHAB-II protocol. AHAB-II participants were recruited between February 2008 and October 2011 through mass mailings of recruitment letters to individuals randomly selected from voter registration and other public domain lists. All participants were between 30 and 54 years of age and employed at least 25 hours per week. During screening, volunteers provided sociodemographic and substance use information. Among other assessments, medical history and detailed listing of all prescription and non-prescription medications and supplements were reviewed by a study nurse, and anthropometric measurements (e.g. height, weight) were obtained. The following exclusion criteria were applied: (a) history of cardiovascular disease, schizophrenia or bipolar disorder, chronic hepatitis, renal failure, major neurological disorder, lung disease requiring treatment, or stage 2 hypertension (SBP/DBP ≥ 160/100); (b) cancer if requiring treatment in the past 12 months, (c) high alcohol consumption (≥ 5 portions 3–4 times per week); (d) use of fish-oil supplements (because of the requirements for an AHAB-II substudy); (e) use of insulin, glucocorticoid, antiarrhythmic, antihypertensive, lipid-lowering, psychotropic, or prescription weight-loss medications; (f) pregnancy; or (g) shift work schedules. The AHAB-II protocol was approved by the University of Pittsburgh Institutional Review Board and informed consent was obtained at enrollment.