Abstract
Psychostimulants can be employed as a countermeasure to cognitive declines resulting from insufficient sleep. Although caffeine is the most consumed psychostimulant, consumption can cause adverse side-effects, including sleep disturbance. Therefore, there is interest in identifying alternative supplements that improve cognitive performance without compromising subsequent sleep. Here we investigate the influence of the dose and timing of theacrine consumption on cognitive performance and subsequent sleep using conditions that replicate a low (100 mg) and high (400 mg) dose consumed in the morning (12 h prior to bedtime), afternoon (eight hours prior to bedtime), and evening (four hours prior to bedtime). We found no significant effect of the low or high theacrine dose on subsequent sleep although the high dose showed small non-significant effects on sleep efficiency and wake after sleep onset at each timepoint of consumption. However, consuming theacrine within eight hours of bedtime improved next-morning cognitive performance, with the 400 mg dose reducing the number of lapses on the Psychomotor Vigilance Task, although there were no significant effects on reaction time. Our findings provide initial scientific evidence suggesting that theacrine consumption may improve some aspects of next-morning cognitive performance but not others, with small non-significant effects on nighttime sleep.