The Impact of Different Types of Higher Dietary Protein Intake on Sleep Quality in Singapore Older Adults: A Randomized Controlled Trial

Objectives: Sleep is an essential part of health and well-being but, as people age, their sleep quality decreases. Higher protein (PRO) intake was suggested to promote sleep. A recent study reported that plant-based PRO intake was associated with better sleep quality. But data from randomized controlled trial (RCT) assessing the effect of PRO source on sleep quality is few, hence, we aim to assess the impact of both PRO quantity and source on sleep quality in older adults. Methods: This study is a single-blinded, 16-week parallel RCT. Subjects (66 ± 4 yrs, mean ± SD) were randomly assigned to either the control (normal PRO; n=14) or higher PRO group. Those in the higher PRO group were asked to consume 30g casein PRO (n=12) or 30g soy PRO (n=16) 30 min before bed daily. In the study, subjects were instructed to follow Singapore's healthy eating pattern. Sleep quality data were collected every 4 weeks by the Pittsburg Sleep Quality Index (PSQI) questionnaire and actigraphy watch. A global sleep score (GSS) was obtained from the PSQI, and a lower score shows better sleep quality. Other sleep quality components (sleep duration, sleep latency, sleep efficiency) were also extracted. The impact of the PRO supplements on sleep quality were evaluated by mixed ANOVA. Results: A significant time and PRO intake effect on GSS was detected (pinteraction=0.024) at week 8. A decrease in GSS was observed in both the PRO groups (Casein: -0.5 ± 1.5; Soy: -1.4 ± 2.0) but GSS increased in the control group (Control: 0.79 ± 1.67). Only the soy PRO group showed a significant GSS reduction from baseline (p=0.012). At week 16, however, this effect no longer exists. No changes in other sleep quality components were detected based on PRO quantity and source. Conclusions: In older adults, bedtime PRO intake can improve sleep quality up to 8 weeks, with a more favorable effect of soy PRO. This may be due to the difference amino acid composition of the PRO source. Funding Sources: NUS Mind-Science Centre.