Acute fasting reduces tolerance to progressive central hypovolemia in humans.

Potential health benefits of an acute fast include reductions in blood pressure and increases in vagal cardiac control. These purported health benefits could put fasted humans at risk for cardiovascular collapse when exposed to central hypovolemia. The purpose of this study was to test the hypothesis that an acute 24-h fast (vs.

Core body temperature changes before sleep are associated with nocturnal heart rate variability.

Core body temperature (CBT) reductions occur before and during the sleep period, with the extent of presleep reductions corresponding to sleep onset and quality. Presleep reductions in CBT coincide with increased cardiac parasympathetic activity measured via heart rate variability (HRV), and while this appears to persist into the sleep period, individual differences in presleep CBT decline and nocturnal HRV remain unexplored. The purpose of the current study was to assess the relationship between individual differences in presleep CBT reductions and nocturnal heart rate (HR) and HRV in a population of 15 objectively poor sleeping adults [10 males, 5 females; age, 33 ± 4 yr; body mass index (BMI) 27 ± 1 kg/m] with the hypothesis that blunted CBT rate of decline would be associated with elevated HR and reduced nocturnal HRV.

Daily cannabis use is associated with sleep duration differentially across ages.

Objective: To assess the relationship between frequency of cannabis use and sleep duration across age in a large US population (235,667 people).

Methods: Multinomial logistic regression was used to evaluate the association between the frequency of cannabis use and sleep duration using cross sectional data from the 2016-2018 Behavioral Risk Factor Surveillance System.

Results: When adjusted for sociodemographic factors, health related variables, and stratified by age we found that young adults (18-44 years) who reported daily-use (≥16 uses a month) had an increased risk ratio (RR [95% CI]) for either short or long sleep (1.

Influence of an acute fast on ambulatory blood pressure and autonomic cardiovascular control.

Evidence suggests that intermittent fasting improves cardiovascular health by reducing arterial blood pressure, but contributing mechanisms are unclear. The purpose of this study was to determine the influence of an acute fast on hemodynamics, muscle sympathetic nerve activity (MSNA), and autonomic control at rest and during an arterial pressure challenge. Twenty-five young normotensive volunteers were tested twice, in the fed and fasted (24 h) states (randomized).

Controlled breathing and autonomic rhythms: Influence of auditory versus visual cues.

We compared standard metrics of autonomic control in 20 humans (10 female) during spontaneous and controlled breathing. Subjects controlled breathing at 0.25 Hz following a metronome (auditory) or scrolling waveforms (visual).

Acute effects of electronic cigarettes on arterial pressure and peripheral sympathetic activity in young nonsmokers.

Electronic cigarettes (e-cigarettes) are marketed as an alternative to smoking for those who want to decrease the health risks of tobacco. Tobacco cigarettes increase heart rate (HR) and arterial pressure, while reducing muscle sympathetic nerve activity (MSNA) through sympathetic baroreflex inhibition. The acute effects of e-cigarettes on arterial pressure and MSNA have not been reported: our purpose was to clarify this issue.