Abnormalities of the autonomic nervous system have been repeatedly shown in hypertension. We studied the associations between being overweight, blood pressure, cardiac vagal tone as measured by variability in heart rate, and well-being in a large cohort of young men. We hypothesised an inverse correlation between body mass index and the variability in heart rate. Further, we assessed systolic and diastolic blood pressure as traditional indicators of cardiovascular risk. Exclusion criteria were the use of drugs or pharmaceuticals. The following data from 786 men with a mean age of 19.4 years (standard deviation = 1.4, with a range from 16 to 24 years) were analysed in a cross-sectional study: body mass index, sleep duration, sporting activities, psychological well-being, blood pressure, heart rate, and variability in heart rate. Despite the young age of the men in this study, increased values for the body mass index were already associated with a shift in sympathovagal balance trending towards sympathetic dominance. There was also a significant positive correlation between body mass index and systolic and diastolic blood pressure. A multiple stepwise regression analysis showed that significant factors, which were associated with variability in heart rate, were body mass index and sporting activities. In addition, sporting activity and sleep duration had a significant positive impact on psychological well-being. Even in young men, being overweight is associated with increased cardiovascular risk, especially an increased sympathetic and/or lowered cardiovascular tone and increased blood pressure. Our study gives additional motivation for the early prevention and treatment of obesity in childhood and adolescence.

THC administration, there is a decrease in vagal tone that is accompanied by an increase in sympathetic activity [7] . These fi ndings suggest that the increase in heart rate caused by acute administration of THC may be due to an interaction with the autonomic nervous system. However, a direct cardiac eff ect of THC cannot be excluded [17] . With repetitive THC dosing, there is a transition from increased to decreased sympathetic activity and from decreased to increased parasympathetic activity [1,8] . Prolonged use of cannabis in humans elicits a long-lasting decrease in blood pressure and heart rate [5] . We were able to study the associations between cannabis consumption and heart rate variability in a large cohort of young men eligible for military service. The data presented here were not collected in the context of a laboratory survey, but rather during everyday life. We hypothesized that prolonged use of cannabis would lead to decreased heart rate, but increased HRV in young men. Wadsworth et al. reported that cannabis use was associated with impairment in both cognitive