Onset of Impaired Sleep and Cardiovascular Disease Risk Factors: A Longitudinal Study

STUDY OBJECTIVES: Impaired sleep has been linked to increased risk of cardiovascular disease (CVD), but the underlying mechanisms are still unsettled. We sought to determine how onset of impaired sleep affects the risk of established physiological CVD risk factors (i.e., hypertension, diabetes, and dyslipidemia). METHODS: In a longitudinal cohort study with 3 survey waves (2000, 2004, 2008) from the Finnish Public Sector study we used repeated information on sleep duration and disturbances to determine onset of impaired sleep. Information on development of CVD risk factors, as indicated by initiation of medication for hypertension, diabetes, and dyslipidemia was derived from electronic medical records within 8 years of follow-up. Data on 45,647 participants was structured as two data-cycles to examine the effect of change in sleep (between two waves) on incident CVD events. We applied strict inclusion and exclusion criteria to determine temporality between changes in sleep and the outcomes. RESULTS: While we did not find consistent effects of onset of short or long sleep, we found onset of disturbed sleep to predict subsequent risk of hypertension (hazard ratio = 1.22, 95% CI: 1.04-1.44) and dyslipidemia (HR = 1.17, 95% CI: 1.07-1.29) in fully adjusted analyses. CONCLUSIONS: Results suggest that onset of sleep disturbances rather than short or long sleep mark an increase in physiological risk factors, which may partly explain the higher risk of CVD observed among impaired sleepers. COMMENTARY: A commentary on this paper appears in this issue on page 1629.