2.4. Procedure
Participants attended four appointments as part of the study protocol: a screening appointment, a training visit and two testing visits. The remote screening session was conducted via telephone and encompassed several key components. These included an explanation of the trial requirements, signing of an electronic consent form, collection of demographic information, review of the self-reported health screening encompassing the inclusion and exclusion criteria and calculation of caffeine intake (via the Caffeine Consumption Questionnaire (CCQ)). Following the telephone screening, the participants who met the eligibility criteria proceeded to attend a training visit, during which they signed a paper consent form. Physiological data, which could not be gathered remotely, including blood pressure, height, weight and waist-to-hip ratio (WHR) were also collected at this visit. Participants received training on the cognitive tasks and mood assessment scales, ensuring their understanding of the task instructions and test procedures. This training assessment also allowed for identification and exclusion of participants who were unable or unwilling to perform at a minimum standard.For the two subsequent laboratory-based testing sessions (referred to as Day 1 and Day 29), the participants arrived at the laboratory at either 8 am or 10 am (consistent between visits). Prior to their arrival, participants consumed a standardised breakfast of cereal or toast, ensuring that it was no later than an hour before their scheduled appointment. They also refrained from caffeine since waking and from alcohol for the 24 h before each visit. Upon arrival at the laboratory, the participants completed the PSS and their baseline cognitive assessment. They then consumed their treatment for that day and, following a 60 min absorption period, they completed a second cognitive assessment. The testing protocol on Day 29 mirrored that of Day 1, with one exception: after completing the Day 1 assessments, the participants were provided with a treatment diary and the treatments that they would consume between the visits. On Day 29 the participants returned their remaining treatments and diary so that compliance could be calculated, and at the end of the session the participants were asked to complete a treatment guess form. Each testing visit had a duration of 2 h, as illustrated in 