Caffeine affects cardiovascular and neuroendocrine activation at work and home.
OBJECTIVE
This study investigated the effects of moderate doses of caffeine on ambulatory blood pressure and heart rate, urinary excretion of epinephrine, norepinephrine, and cortisol, and subjective measures of stress during normal activities at work and at home in the evening.


METHODS
Healthy, nonsmoking, habitual coffee drinkers (N = 47) participated in 3 days of ambulatory study. After a day of ad lib caffeine consumption, caffeine (500 mg) and placebo were administered double-blind in counter-balanced order on separate workdays. Ambulatory blood pressure and heart rate were monitored from the start of the workday until bedtime. Urinary excretion of catecholamines and cortisol was assessed during the workday and evening.


RESULTS
Caffeine administration significantly raised average ambulatory blood pressure during the workday and evening by 4/3 mm Hg and reduced average heart rate by 2 bpm. Caffeine also increased by 32% the levels of free epinephrine excreted during the workday and the evening. In addition, caffeine amplified the increases in blood pressure and heart rate associated with higher levels of self-reported stress during the activities of the day. Effects were undiminished through the evening until bedtime.


CONCLUSIONS
Caffeine has significant hemodynamic and humoral effects in habitual coffee drinkers that persist for many hours during the activities of everyday life. Furthermore, caffeine may exaggerate sympathetic adrenal-medullary responses to the stressful events of normal daily life. Repeated daily blood pressure elevations and increases in stress reactivity caused by caffeine consumption could contribute to an increased risk of coronary heart disease in the adult population.
Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC 27710, USA. jdlane@acpub.duke.edu
James D
JD
Lane
Carl F
CF
Pieper
Barbara G
BG
Phillips-Bute
John E
JE
Bryant
Cynthia M
CM
Kuhn
D000328:Adult; D002110:Caffeine / Q000008:administration & dosage / Q000009:adverse effects*; D002395:Catecholamines / Q000378:metabolism* / Q000652:urine; D000697:Central Nervous System Stimulants / Q000008:administration & dosage / Q000009:adverse effects*; D002851:Chromatography, High Pressure Liquid; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004837:Epinephrine / Q000378:metabolism*; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism* / Q000652:urine; D006973:Hypertension / Q000139:chemically induced*; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000378:metabolism*; D010913:Pituitary-Adrenal System / Q000187:drug effects; D017132:Workplace
D002395:Catecholamines; D000697:Central Nervous System Stimulants; D002110:Caffeine; D006854:Hydrocortisone; D009638:Norepinephrine; D004837:Epinephrine