Hemodynamic effects of dietary caffeine, sleep restriction, and laboratory stress


  • This work was supported by the European Commission Fifth Framework Programme, Grant No. QLK1-CT-2000-00069. The views expressed in this report are the sole responsibility of the authors, and do not necessarily reflect the views of the European Commission or its services or their future policy in this area. The authors gratefully acknowledge the assistance of Dr. Marian Kane and Frances Harte, who developed the EIA technique and performed the saliva assays. Acknowledgment is also due to John Dring and Declan Coogan for their technical assistance and to Deirdre McGuire, Christina Casey, and Grainne Cousins, who assisted with data collection.

Address reprint requests to: Professor Jack E. James, Department of Psychology, National University of Ireland, Galway, Ireland; e-mail: j.james@nuigalway.ie.


This study examined the separate and interactive effects of caffeine, sleep restriction, and task-induced laboratory stress in 96 healthy male and female volunteers. Participants alternated weekly between ingesting placebo and caffeine (1.75 mg/kg) three times daily for 4 consecutive weeks, while being either rested or sleep restricted. Finapres measurements of blood pressure, cardiac output, and total peripheral resistance showed that caffeine produced persistent blood pressure increases with a vascular hemodynamic profile. Sleep restriction produced a pronounced vascular response not associated with appreciable changes in blood pressure, whereas blood pressure increases induced by cognitive activity showed mixed cardiac and vascular responses. The findings suggest that life-long dietary caffeine may contribute significantly to the development of cardiovascular disease.