Nutritional Modulation of Sleep Latency, Duration, and Efficiency: A Randomised, Repeated-Measures, Double-Blind Deception Study

Purpose To test the hypothesis that a novel nutritional blend comprised of tryptophan, glycine, magnesium, tart cherry powder and L-theanine, enhances subjective and objective measures of sleep during free living conditions. Methods In a randomised, repeated measures crossover and double blind deception design, participants (n = 9 male and 7 female; age: 24 ± 3 years; body mass: 69.8 ± 11.6 kg; stature: 170.8 ± 9.1 cm) completed a 3 day familiarisation period, followed by 3 day intervention and placebo trials. Subjective Pittsburgh Quality Sleep Index, Core Consensus Sleep Diary and Karolinska Sleepiness Scale survey tools, alongside objective actigraphy measures of sleep were assessed, with daily nutritional intake, activity and light exposure standardised between trials. Participants provided daily urine samples for assessment of targeted and untargeted metabolomes. Results The intervention trial reduced sleep onset latency (-24 ± 25 mins; p = 0.002), increased total sleep time (22 ± 32 mins; p = 0.01) and sleep efficiency (2.4 ± 3.9 %; p = 0.03), whilst also reducing morning sleepiness (p = 0.02). Throughout the study, 75 % of participants remained blinded to sleep assessment as a primary outcome measure, with 56 % subjectively indicating improved sleep during the intervention trial. Metabolomic analysis highlighted several significantly altered metabolomes related to sleep regulation between trials, inclusive of 6-sulfatoxymelatonin, D-serine and L-glutamic acid. Conclusions Data demonstrate that employing the proposed blend of novel nutritional ingredients during free living conditions reduced sleep onset latency, increased total sleep duration and increased sleep efficiency, leading to reduced perceptions of morning sleepiness. These effects may be mediated by the upregulation of key metabolites involved in the neurophysiological modulation of the sleep/wake cycle