Sleep requirements change across the lifespan and quality of sleep declines as we age(Reference Madrid-Valero, Martínez-Selva and Couto1). Poor sleep across adulthood has been associated with ramifications on subjective health, quality of life(Reference Magee, Caputi and Iverson2) and advancement of cognitive decline and dementia(Reference Hudon, Escudier and De Roy3). Among the modifiable factors that are posited to contribute to sleep quality, diet and nocturnal metabolism are thought to be strong predictors of sleep quality(Reference St-Onge, Mikic and Pietrolungo4).
The aim of the current study was to evaluate the effectiveness of nutritional formulation (delivered in a powdered- based drink) containing 0.75 g Mulberry Leaf Extract (0.75g) and a natural source of Tryptophan (120mg) consumed concurrently with an evening-meal (Glycemic load of 55 ± 10%) to promote better sleep and next-day mood and cognitive performance in healthy adult poor sleepers.
The clinical trial was a double-blind, controlled, randomized, 2-arm, sequential groups cross-over design (ClinicalTrials.gov Identifier: NCT05372900). Adult (aged 25–50), self-identified poor sleepers (confirmed by Pittsburg Sleep Quality Index >5 and <85% mean sleep efficiency over 14-days at screening) received standardized meals and concurrent daily intake of the nutritional formulation or placebo approximately 4 hours before bedtime. Intervention phases lasted 14-days with a 28- to 42-day washout period in-between. Primary outcomes were Sleep Efficiency (SE) and Sleep Onset Latency (SOL) measured by actigraphy. Secondary outcomes included inter alia: mood (Brief Mood Introspection Scale), sleep quality (Karolinska Sleepiness Scale) and objective cognitive performance measures (Psychomotor Vigilance Task, 2-back task, NASA Task Load Index) taken at breakfast, lunch and dinner time (1–1.5- hours, 6- and 12-hours post-wake respectively).
Linear mixed model analysis was conducted with intention-to-treat, adjusting for baseline and treatment order for sleep, mood, and cognitive outcomes. Consumption of the active treatment resulted a significant improvement in SOL (actigraphy= -3.48 mins, p = .026; self- report =−16.7mins, p = .031) compared to control. There was no significant effect on SE (p = .230). Sleep and mood self-report measures showed that participants felt significantly less sleepy (p = .041) and more aroused (p = .026) the next morning. Interestingly, cognitive performance was improved on several tests throughout the next day at breakfast, lunch and dinner assessment points: For psychomotor vigilance, reaction time (p = .598, p = .051, p= .024 respectively) and number of lapses, where lapses are characterized as those made within 698 ms (2x median reaction time for the cohort) showed significant improvement (p = .027, p = .005, p = .004 respectively). Participants also reported actively feeling these performance improvements (performance dimension of NASA TLX) following treatment compared to control conditions (p = .014, p = .063, p = .010, respectively).Our findings demonstrate that sleep onset, quality and next day cognitive performance can be ameliorated by a daily dinner time supplemental nutritional intervention and may represent a convenient strategy to support the betterment of sleep and mood and cognitive benefits in adult populations.
