Author(s): BARNARD, J., ROBERTS, S., LASTELLA, M., CALLAHAN, D., AISBETT, B., CONDO, D., Institution: DEAKIN UNIVERSITY, Country: AUSTRALIA, Abstract-ID: 1494

INTRODUCTION:
Sleep is vital for optimal recovery and sporting performance (1). Recently, protein has been identified as a dietary factor influencing the sleep of athletically trained populations (2), whereby the type and timing of protein appears crucial in the protein-sleep relationship (3). Evening consumption of a whey protein rich in the amino acid tryptophan (TRP), alpha-lactalbumin (ALAC), has previously shown to benefit sleep - particularly among poor sleepers (4). Given trained populations often experience sleep difficulty (5), this study sought to investigate whether acute evening supplementation of ALAC would influence sleep outcomes, and next-day cognitive performance within a trained population with sleep difficulties.
METHODS:
Nineteen trained males (n=8) and females (n=11) with sleep difficulties aged 18-40 completed this double-blinded, counterbalanced, randomised, cross-over trial. 40 g ALAC (1.9 g TRP) or an isocaloric placebo (collagen) were supplemented two hours prior to individualised bedtime for three consecutive nights in a controlled environment, with sleep measured using portable electroencephalography (DREEM 3). Diet was standardised to 1.2 g/kg body weight protein throughout the day, with a low-protein dinner provided two hours prior to the supplement to limit confounding effects on TRP levels. On the first night of each intervention period, blood samples were taken across five evening timepoints (0, 30, 60, 90, 120 min post-supplement) prior to bedtime. A tablet-based testing battery (Joggle Research) assessing multiple cognitive domains was completed next day, thirty minutes after waking. Mixed models were used to assess the effect of treatment on sleep variables and cognition, with time added as a fixed effect to determine the treatment and time interaction for plasma TRP concentrations.
RESULTS:
During the ALAC condition, participants had an increased NREM stage 2 sleep duration (PLA 205.9 ± 33.3, ALAC 216.5 ± 33.1 min); improved reaction time in cognitive tests involving sensory motor speed, spatial orientation, and vigilant attention (p<0.05); and raised plasma TRP across all timepoints compared to 0 min (p<0.01). No other sleep or cognitive outcomes were affected by ALAC supplementation.
CONCLUSION:
Pre-sleep ALAC supplementation increased NREM stage 2 sleep, improved morning cognition, and augmented plasma TRP levels compared to placebo. With NREM stage 2 sleep being important for brain plasticity and motor learning (6, 7), acute supplementation of ALAC may prove beneficial to trained individuals with sleep difficulties looking to assist next-day performance. Future research should investigate the impact of chronic ALAC supplementation on sleep and next-day sporting performance within a trained population with sleep difficulties.

REFERENCES:
(1) Lastella et al. 2015, (2) Barnard et al. 2022, (3) Falkenberg et al. 2021, (4) Barnard et al. 2024, (5) Roberts et al. 2018, (6) Boutin & Doyon 2020, (7) Walker et al 2003