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

Langan-Evans, Carl, Hearris, Mark A., Gallagher, Chloe, Long, Stephen, Thomas, Craig, Moss, Andrew D., Cheung, William, Howatson, Glyn and Morton, James P. (2023) Nutritional Modulation of Sleep Latency, Duration, and Efficiency: A Randomized, Repeated-Measures, Double-Blind Deception Study. Medicine & Science in Sports & Exercise, 55 (2). pp. 289-300. ISSN 0195-9131

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Abstract

Purpose
This study aimed to test the hypothesis that a novel nutritional blend composed of tryptophan, glycine, magnesium, tart cherry powder, and l-theanine enhances subjective and objective measures of sleep during free living conditions.

Methods
In a randomized, repeated-measures crossover and double-blind deception design, participants (n = 9 males and 7 females, age = 24 ± 3 yr, body mass = 69.8 ± 11.6 kg, stature = 170.8 ± 9.1 cm) completed a 3-d familiarization period, followed by 3-d 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 standardized between trials. Participants provided daily urine samples for assessment of targeted and untargeted metabolomes.

Results
The intervention trial reduced sleep onset latency (−24 ± 25 min; P = 0.002), increased total sleep time (22 ± 32 min; P = 0.01), and increased sleep efficiency (2.4% ± 3.9%; P = 0.03), while 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 using 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.

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