Three issues raised by M. W. Eysenck and Folkard are discussed. These include (a) just what individual difference variable is mediating the time of day and caffeine effects; (b) what the difference is in the diurnal rhythms of low and high impulsives; and (c) whether it is necessary to postulate multiple activation states. Suggestions for future research are then given.
No takes yet. Share an insight, caveat, or question.
Humphreys et al. (1980) studied this question.
Synapse has enriched 2 closely related papers on similar clinical questions. Consider them for comparative context: