The importance of cardiorespiratory fitness and sleep duration in early CVD prevention. BMI, resting heart rate and questions about sleep patterns are suggested in risk assessment of young adults, 18-25 years.

Background: Cardiorespiratory fitness (CRF) and sleep habits are lifestyle factors with potential to prevent cardiovascular disease (CVD). CVD is the leading cause of death worldwide, it is therefore important to establish a healthy lifestyle at young age. In the Lifestyle, biomarkers and atherosclerosis (LBA) study we have examined 834 healthy non-smoking adults, 18-25 years. The general purpose of the LBA study was to study the effect of lifestyle on traditional biomarkers known to influence CVD risk. The aims of the present study were to evaluate sleep habits of the young adult women and men participating in the LBA study, and to compare the importance of sleep habits and other lifestyle habits on clinically relevant biomarkers for CVD. Additional aim was to find easy and reliable non-invasive biomarkers to detect young adults with increased risk to develop CVD later in life. Methods: The participants have previously been examined for lifestyle factors, biomarkers and CVD risk score. They filled in a validated computerized questionnaire about their general physical and mental health. The questionnaire included questions on sleep duration and experienced quality of sleep. Results: In total 27% of the young adult participants reported difficulties to fall asleep or experiences anxious sleep with several awakenings per night. The experienced anxious sleep was not related to higher CVD risk score, but sleep quality and sleep duration was correlated. Shorter sleep duration was significantly associated to higher body mass index (BMI), body fat %, homeostasis model assessment of insulin resistance (HOMA-IR) and CVD risk. The modifiable lifestyle factor with highest odds ratio (OR) for CVD risk was CRF. Sleep duration was the second most influential lifestyle factor, more important than moderate- and vigorous physical activity (MVPA) and food habits. Correlations between CRF and heart rate (HR) (P<0.01) and HOMA-IR and BMI (P<0.01) was observed, indicating that BMI and resting HR in combination with questions about sleep patterns are easy and reliable non-invasive biomarkers to detect young adults who needs counselling about a healthy lifestyle. Conclusion: Decreased sleep duration in combination with decreased CRF, in young adults, is a serious health issue.