BACKGROUND: High cardiorespiratory fitness (CRF), healthy physical activity (e.g., taking >10,000 steps per day) and sleep habits (e.g., sleeping 7-9 hours per night) decrease the risk of all cause mortality. However, the association between CRF and physical activity with sleep are understudied and inconclusive. Thus, we sought to examine the associations between CRF and physical activity with objective and subjective sleep metrics. METHODS: Thirty-two adults (14 female, age 40 ± 18 years, body mass index [BMI] 25.8 ± 6.2 kg/m2) participated in this study. We assessed CRF using a graded treadmill exercise test to volitional exhaustion to determine relative VO2peak (mL/kg/min). We assessed physical activity using waist worn ActiGraph GT3X accelerometers for a minimum of 5-days (11.8 ± 3.6 days) to obtain average daily steps and moderate and vigorous physical activity (MVPA). Participants’ self-reported sleep quality was assessed using the Pittsburg Sleep Quality Index (PSQI) scored 0 [better] to 21 [worse]. Objective nightly sleep duration (hours) and efficiency (% of time in bed spent sleeping) were measured using Phillips Actiwatch Spectrum PLUS accelerometers (worn on the wrist) for a minimum of 5-days (7.1± 0.5 days days). All variables were tested for normality using the Shapiro Wilk test. We used Pearson’s r and Spearman’s rho correlations controlled for age, sex and BMI to examine associations between CRF and physical activity with sleep quality variables. Significance was set as p ≤ 0.05. RESULTS: After controlling for age, sex and BMI there was an association between VO2peak and sleep duration (r = 0.428, p = 0.021), but not PSQI (rho = -0.202, p = 0.313), or sleep efficiency (r = 0.168, p = 0.384). MVPA was not associated with PSQI (rho = -0.207, p = 0.395), sleep duration (r = 0.301, p = 0.185), or sleep efficiency (r = 0.222, p = 0.333). Steps were also not associated with PSQI (rho = -0.230, p = 0.344), sleep duration (r = 0.298, p = 0.189), or sleep efficiency (r = 0.258, p = 0.258). CONCLUSIONS: Our preliminary data indicate there is an association between cardiorespiratory fitness and objectively measured sleep duration, but not sleep efficiency, or subjective sleep quality. Physical activity was not associated with sleep. Additional data are needed to determine directionality between cardiorespiratory fitness, sleep duration, and potential mechanisms.

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