Effect of Creatine Supplementation on Cognitive Performance and Frontal Haemodynamics Following Acute Sleep Restriction: A Randomised, Double-Blind, Placebo-Controlled Crossover Pilot Study

Background Sleep restriction (SR) impairs cognitive performance and cerebral metabolism. Creatine supplementation may elicit a metabolic and cognitive benefit following sleep loss. Methods A randomised, cross-over trial ([ACTRN12626000301369]; retrospectively registered) was conducted with 8 healthy adults (4 women, 4 men). Cognitive performance, mood, sleepiness, perceived workload and cerebral haemoglobin oxygenation were compared between a night of unrestricted sleep and a night restricted to 3 h time-in-bed (i.e. SR), separated by 7 days of unrestricted sleep and ingestion of either 20 g⋅day −1 creatine monohydrate or tapioca (placebo). At least a 5-week washout period separated trials. Data were analysed with linear mixed models, t -tests and equivalence tests. Results SR slowed mean reciprocal response time and mean fastest 10% reaction time (RT), increased fatigue, workload and sleepiness, and reduced vigour (all p < 0.05). However, SR had no effect on lapses, mean slowest 10% RT, running memory continuous performance test RT and number of correct responses per minute, logical reasoning-symbolic test RT and number of correct responses per minute, Stroop interference score, and task-evoked cerebral haemoglobin oxygenation (all p > 0.05). Creatine supplementation had no effect on any cognitive or physiological variable (all p > 0.05). Equivalence testing demonstrated equivalence for mean fastest 10% RT, mean slowest 10% RT and RMCPT throughput (all p < 0.05); for all other variables the tests were inconclusive ( p > 0.05), so a meaningful effect of creatine cannot be excluded. Conclusions These data do not support an effect of creatine supplementation on cognition or cerebral haemoglobin oxygenation following a single night of sleep restriction; however, the study was insufficiently powered to confirm or exclude such effects.