ABSTRACT
One of the earliest laboratory studies of the effects of caffeine on mental performance carried out under carefully controlled conditions was published more than 80 years ago. The study (Hollingworth, 1912) employed a placebocontrolled and double-blind design in which the effects of caffeine were assessed on sleep and several tests of human performance. The main conclusion was that caffeine possesses clearly properties for the facilitation of performance. Further study was found necessary to elucidate the mechanisms underlying the observed caffeine effects. Since then a number of studies have confirmed these early observations (Weiss and Laties, 1962), but the literature also includes many conflicting and ambiguous reports of caffeine’s effects. In fact, despite a large number of papers, some of the more recent reviews (Bättig, 1985; Dews, 1984) found it difficult to arrive at a coherent account of the principal effects of caffeine on human performance.
