title: Cumulative neurobehavioral and physiological effects of chronic caffeine intake: individual differences and implications for the use of caffeinated energy products.
abstract: The use of caffeine-containing energy products has increased worldwide in recent years. All of the top-selling energy drinks contain caffeine, which is likely to be the primary psychoactive ingredient in these products. Research shows that caffeine-containing energy products can improve cognitive and physical performance. Presumably, individuals consume caffeine-containing energy products to counteract feelings of low energy in situations causing tiredness, fatigue, and/or reduced alertness. This review discusses the scientific evidence for sleep loss, circadian phase, sleep inertia, and the time-on-task effect as causes of low energy and summarizes research assessing the efficacy of caffeine to counteract decreased alertness and increased fatigue in such situations. The results of a placebo-controlled experiment in healthy adults who had 3 nights of total sleep deprivation (with or without 2-hour naps every 12 hours) are presented to illustrate the physiological and neurobehavioral effects of sustained low-dose caffeine. Individual differences, including genetic factors, in the response to caffeine and to sleep loss are discussed. The review concludes with future directions for research on this important and evolving topic.
authors.affiliation: Department of Psychology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Spaeth
authors.forename: Namni
authors.initials: N
authors.lastname: Goel
authors.forename: David F
authors.initials: DF
authors.lastname: Dinges
mesh_terms: D001288:Attention / Q000187:drug effects*; D002110:Caffeine / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D002940:Circadian Rhythm / Q000187:drug effects; D061215:Energy Drinks; D005221:Fatigue / Q000517:prevention & control; D006801:Humans; D057285:Precision Medicine; D012890:Sleep / Q000187:drug effects*; D012892:Sleep Deprivation / Q000188:drug therapy
chemical_list: D000697:Central Nervous System Stimulants; D002110:Caffeine
keywords: alertness; caffeine; circadian rhythm; energy drinks; fatigue