Why are caffeine-containing drinks so popular? How does caffeine affect mood and alertness? Is caffeine a cognitive enhancer? Is caffeine healthy? Answers to these questions are provided by over 100 years of research on caffeine and human behaviour.

Caffeine is consumed predominantly in tea (the second most consumed drink after water) and coffee (which ranks second only to oil in terms of monetary value traded worldwide), and its popularity derives at least in part from the perception that it is a helpful psychostimulant. Unfortunately, this perception does not match the reality of the everyday consumption of caffeine.

Recent research in the NBU has shown that the alerting and associated effects of caffeine on sustained attention experienced by frequent caffeine consumers represent withdrawal reversal rather than a net benefit for functioning. That is, frequent consumers become tolerant to the effects of caffeine on wakefulness, and cessation of consumption (even for no more than 6-8 hours) causes sleepiness – which is reversed by taking some more caffeine. Tolerance also develops to the tendency for caffeine to increase anxiety, but not to its independent effect on motor (physical) performance. An important (largely unconscious) motive for consuming is avoidance of withdrawal. Over the longer term, consumption of tea and consumption of coffee seem to reduce risk of cognitive decline in older age, possibly because of beneficial actions of compounds other than caffeine that are present in these drinks.

Recent articles: 

• Keenan, EK, Tiplady, B, Priestley, CM & Rogers, PJ 2014, 'Naturalistic Effects of Five Days of Bedtime Caffeine Use on Sleep, Next-Day Cognitive Performance, and Mood' Journal of caffeine research, vol 4, no. 1, pp. 13-20. Link to article
• Rogers, PJ, Heatherley, SV, Mullings, EL, & Smith, JE 2013, 'Faster but not smarter: effects of caffeine and caffeine withdrawal on alertness and performance'. Psychopharmacology, vol 226, no. 2,pp. 229-240. Link to article
• Smith, JE, Lawrence, AD, Diukova, A, Wise, RG & Rogers, PJ 2012, 'A storm in a coffee cup? Caffeine modulates neural response to social signals of threat' Social Cognitive and Affective Neuroscience, vol 7, no. 7, pp. 831-40. Link to article
• Diukova, A., Ware, J., Smith, J. E., Evans, C. J., Murphy, K., Rogers, P. J., & Wise, R. G. 2012, Separating neural and vascular effects of caffeine using simultaneous EEG-FMRI: Differential effects of caffeine on cognitive and sensorimotor brain responses.NeuroImage, 62(1), 239-249. Link to article
• Attwood, AS, Rogers, PJ, Ataya, AF, Adams, S & Munafò, MR 2012, 'Effects of caffeine on alcohol-related changes in behavioural control and perceived intoxication in light caffeine consumers' Psychopharmacology, vol 221, no. 4, pp. 551-60. Link to article
• Rogers, PJ, & Smith, JE 2011, 'Caffeine, mood and cognition'. In D. Benton (Ed.), Lifetime nutritional influences on cognition. behaviour and psychiatric illness. (pp. 251 - 271). Woodhead Publishing.