OBJECTIVE: Sleep is crucial during infancy and supports health and development. Tryptophan is influential in the sleep/wake cycle, and studies have shown that increasing tryptophan intake can improve sleep outcomes. Consumption of alpha-lactalbumin increases ratios of tryptophan to large neutral amino acids (LNAA), an indicator of brain concentrations associated with sleep latency. The objective was to evaluate whether an infant formula with added alpha-lactalbumin improves sleep quality, indicated by nighttime feeding patterns. METHOD: Healthy infants born at full term were randomized to study formula (SF) with added alpha-lactalbumin or a formula with identical protein content without added alpha-lactalbumin (CF). Feeding patterns were assessed over 24 weeks and serum amino acids were measured at week 16. Groups were compared using repeated-measures mixed models and Wilcoxon rank-sum test, and the relationship between feeding and amino acid concentrations was assessed with correlation analysis. RESULTS: = 0.007) were higher in the SF subgroup. CONCLUSIONS: Clinically relevant longer duration between nighttime feeds was observed in infants in the SF group throughout most of the study, with an average of 32 additional minutes at 16 weeks. Concurrently, infants in the SF group had a higher tryptophan:LNAA ratio, supporting the hypothesis that the addition of alpha-lactalbumin may have positively impacted outcomes associated with sleep quality. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT04218929 and NCT04389606 January 6, 2020, and May 15, 2020, respectively).
Orenstein et al. (Thu,) studied this question.