The study, published in The European Journal of Nutrition, examined how evening meals with or without the supplement blend influenced nocturnal glucose metabolism to affect sleep and downstream outcomes beyond traditional metabolic health.
“In persons with self-reported poor sleep, an evening meal supplement, designed to blunt postprandial glycemic response and enhance sleep propensity, had positive impact on sleep quality and next day positive mood,” wrote researchers from the National University of Singapore Sleep Center and Nestlé Research.
“These findings support a novel approach to improve sleep and encourage further research using postprandial glucose response (PPGR) modulation as an intervention [to improve] sleep in persons with subjective sleep complaints.”
The blend, developed by Nestlé, includes mulberry leaf extract to lower postprandial glucose of the evening, tryptophan to facilitate sleep initiation, vitamin B, magnesium, zinc and nutrients to stimulate the body’s melatonin secretion. The product launched in March 2024 as functional component of Yiyang Wanning milk powder, marketed to the 40-to-60-year-old set in the Chinese market.
Sleep and glucose control
Emerging evidence highlights a bi-directional relationship between sleep quality and glucose regulation.
Individuals with poorly controlled type-2 diabetes mellitus tend to experience disrupted sleep patterns, including longer sleep onset latency, greater night-to-night variability and overall lower sleep quality. These sleep disturbances are linked to elevated fasting glucose and insulin levels.
In healthy adults, poor sleep quality has also been associated with increased insulin resistance and glycemic variability. Continuous glucose monitoring (CGM) data show that fluctuations in glucose levels correlate negatively with total sleep time and positively with indicators of sleep fragmentation.
Study details
The randomized, crossover, double-blinded, controlled trial enrolled 43 adults between the ages of 25 and 50 who received standardized meals with a glycemic load of 55 ± 10% supplemented with either a combination of mulberry leaf extract (750 mg, commercially available as Reducose from Phynova), 5.4 g of whey protein containing 120 mg tryptophan, zinc (1.35 mg), magnesium (12.6 mg), vitamin B3 (1.93 mg) and B6 (0.13 mg) or a 4 g wheat protein hydrolysate control.
Both products were provided as a dry powder to be mixed with 200 mL to 250 mL of water at home and consumed within 30 minutes of the standardized evening meal and approximately four hours before bedtime.
Each intervention phase lasted 14 days and was separated by a 28-day washout period. The primary outcomes were actigraphy-measured sleep onset latency and sleep efficiency. Secondary outcomes included continuous glycemic responses, mood and cognition. Objective data was collected through wearable devices that continuously monitored sleep and glucose levels in real-world conditions.
In addition to improved sleep onset latency, reduced sleepiness, increased ‘relaxed’ and ‘vigor’ mood states and expected reduction in PPGR to the evening meal, the study reported a decrease in nocturnal variability.
The PPGR appeared to be a “significant mediator of the treatment effect on SOL, while nocturnal glucose variation was associated with subjective sleep quality ratings,” the researchers wrote.
They also noted that objective sleep onset latency reduction (3.8 min) with the blend was relatively higher than supplement sleep aids like valerian (1.3 min) but lower than melatonin (5.5 min).
No effects were observed on cognition as assessed by a self-administered battery of cognitive tests evaluating vigilance, attention, response inhibition, working memory and short- and long-term memory.
The study called for further research to delineate the respective contributions of the blend’s individual ingredients to sleep onset and sleep quality.
Source: European Journal of Nutrition. doi: 10.1007/s00394-025-03643-8. “Mulberry leaf extract combined with tryptophan improves sleep and post wake mood in adults with sleep complaints – A randomized cross-over study”. Authors: Chun Siong Soon et al.
