Abstract
PURPOSE: In the current study we evaluated a blend of ingredients containing mulberry leaf extract (to lower postprandial glucose of the evening meal), tryptophan (facilitator of the sleep initiation) to benefit sleep initiation and quality in adults with self-reported difficulties with sleep initiation. METHODS: Forty-three adults aged between 25 and 50 years enrolled in a randomized, crossover, double-blind, controlled trial. Participants received standardized meals with a glycemic load of 55 ± 10% and were assigned to receive treatment comprising a combination of mulberry leaf extract (750 mg), whey protein containing 120 mg tryptophan, zinc (1.35 mg), magnesium (12.6 mg), vitamin B3 (1.93 mg) and B6 (0.135 mg) and control (4 g wheat protein hydrolysate). Each intervention phase lasted 14 days separated by a washout period of 28 days. The primary outcomes were actigraphy-measured sleep onset latency and sleep efficiency. Secondary outcomes included continuous glycemic responses, mood, and cognition. RESULTS: A linear mixed model intention-to-treat analysis conducted on 42 participants found that the treatment reduced sleep onset latency (actigraphy: -3.82 mins, p = 0.026; self-report: -3.09 mins, p = 0.048). Treatment significantly reduced evening meal's postprandial glucose response (incremental area under the curve, mmol/L*min) at 1 hour by 21% (p < 0.001), incremental maximum concentration by 16% (p = < 0.001) and nocturnal glucose variation over the 14-day period. Participants on treatment reported improved sleep quality (Karolinska Sleepiness Scale, -0.17, p = 0.041) and feeling more relaxed (Brief Mood Introspection Scale, -0.4, p = 0.003) the next morning compared to when taking the control. Additionally, the treatment improved the vigor dimension on the Profile of Mood Scale (0.8, p = 0.038). No effects were observed on the cognitive performance. Lowering postprandial glucose significantly mediated the treatment effect of lowering sleep onset latency and lower nocturnal glucose variation was also associated with improved sleep quality and next-day positive mood. CONCLUSION: The evening meal supplement benefited sleep initiation and quality, and also improved post wake mood in adults. TRIAL REGISTRATION: Registration number of Clinical Trial - ClinicalTrials.gov NCT05372900.