Grant, Shara S.Kim, KyeFriedman, Bruce H.2023-02-102023-02-102023-01-29Grant, S.S.; Kim, K.; Friedman, B.H. How Long Is Long Enough? Controlling for Acute Caffeine Intake in Cardiovascular Research. Brain Sci. 2023, 13, 224.http://hdl.handle.net/10919/113769Caffeine substantially affects cardiovascular functioning, yet wide variability exists in caffeine control procedures in cardiovascular reactivity research. This study was conducted in order to identify a minimal abstention duration in habitual coffee consumers whereby cardiovascular reactivity is unconfounded by caffeine; Six hours (caffeine’s average half-life) was hypothesized. Thirty-nine subjects (mean age: 20.9; 20 women) completed a repeated measures study involving hand cold pressor (CP) and memory tasks. Caffeinated and decaffeinated coffee were administered. The following cardiovascular indices were acquired during pre-task, task, and post-task epochs prior to coffee intake, 30 min-, and six hours post-intake: Heart rate (HR), high-frequency heart rate variability (HF-HRV), root mean squared successive differences (RMSSD), systolic and diastolic blood pressures (SBP, DBP), mean arterial pressure (MAP), pre-ejection period (PEP), left ventricular ejection time (LVET), systemic vascular resistance (SVR), systemic vascular resistance index (SVRI). Results support the adequacy of a six-hour abstention in controlling for caffeine-elicited cardiovascular changes. The current study offers a suggested guideline for caffeine abstention duration in cardiovascular research in psychophysiology. Consistent practice in caffeine abstention protocols would promote validity and reliability across such studies.application/pdfenCreative Commons Attribution 4.0 InternationalcaffeinecoffeecardiovascularmethodologyautonomicArticle - Refereed2023-02-10https://doi.org/10.3390/brainsci13020224