2.4. Procedure
HOLIDAY, COVID-19 INFECTION
Participants were required to attend six appointments: a remote screening appointment, a training appointment, and four test visits. The remote screening visit was conducted over the telephone, and it comprised a briefing on the requirements of the study, the signing of a virtual consent form, review of the inclusion and exclusion criteria included in the self-reported health screening, completion of the Caffeine Consumption Questionnaire (CCQ), and collection of relevant demographic information such as handedness. Following the initial remote screening, eligible participants were then required to attend a training visit, in which a physical informed consent form was signed. Physiological information that could not be collected remotely, namely, height, weight, waist-to-hip ratio (WHR), and blood pressure (BP), was collected, along with a measure of their usual sleep. Training on the cognitive tasks, EFS, and mood scales was also completed; the completion of cognitive training ensured that participants understood the instructions for both the tasks and the testing procedures and allowed individuals who were unable or unwilling to perform to a minimum standard to be excluded. The first testing visit was at least 48 h and no more than 27 days after the training visit, with each testing visit being 7 days apart (mean 8.55 days ± 5.01; range 5–45 days). Reasons for date deviations more than 14 days were related to COVID-19 infection and/or testing visits falling over the Christmas holiday period.On each of the four testing visits, participants attended the laboratory having followed the pre-visit instructions given at the training visit specifically (a) to consume the same meal no later than an hour before each visit; (b) to avoid caffeine in any form for 12 h prior to the visit; (c) to avoid moderate-to-vigorous physical activity for 24 h prior to the visit; (d) to have a usual night sleep prior to each visit (no more than ±1.5 h according to the self-reported amount at the training visit); and (e) to avoid alcohol for 24 h prior to the visit). Participants first completed the baseline testing battery (picture and word memory task presentation, 4 repetitions of CDB, followed by EFS and mood scales) before being given their assigned treatment beverage and consuming it fully within 10 min. A 60-minute absorption rest period followed, during which participants were instructed to refrain from mobile phone use but were allowed to watch TV or read. At 60 min post-treatment, participants completed the testing battery of four repetitions of CDB and EFS and mood scales again before being given another quiet rest period of 15 min. At 120 min post-treatment, participants completed the testing battery a final time (four repetitions of CDB and EFS and mood scales), along with completing the episodic memory tasks. All testing visits were identical aside from the randomly generated parallel versions of each of the memory tasks and lasted 4–4.5 h in length (