Effects of Selected Nutritional Supplements on Sleep Quality

by | Jun 13, 2022 | 2022, Sleep

Written by Marlene Hollick, Ed.D., R.D. Based on a t-test of matched samples in this double-blind, placebo-controlled, randomized study on the effects of RLX2™ (alpha-s1-casein tryptic hydrolysate & L-Theanine) oral supplement on sleep quality, results indicated that subjects who received this treatment demonstrated significant improvements in reported sleep duration and quality.

woman sleepingSleep quality and quantity play an essential role in how well we function physically as well as emotionally 1-3. Increased rates of accidents, reduced job performance, and increased utilization of healthcare services have been associated with ongoing sleep dysfunction 4. Yet, commonly prescribed remedies for insomnia, including the benzodiazepines and non-benzodiazepine hypnotic agents, are deemed unsatisfactory by some patients and practitioners due to their known side effects, risks of dependence and addition, and withdrawal symptoms 5-7. As a result, some patients prefer alternate methods to help alleviate insomnia and support proper sleep. These alternate approaches include the use of nutritional supplements 8.

Selected as the experimental treatment for this study was alpha-s1-casein tryptic hydrolysate (CTH), a bioactive decapeptide from milk protein hydrolysate associated with calming properties. CTH acts by increasing the inhibition responses of the neurotransmitter GABA, which is associated with sedative and muscle-relaxant outcomes and is being investigated as an insomnia treatment 9,10. Also selected for this study was L-theanine, an amino acid found in green tea, reported to help maintain normal sleep patterns and impart relaxation properties, among other reported attributes 11-14. Similar to the actions of CTH, L-theanine is associated with increasing GABA formation 15.

The participants chosen for this study were from the academic staff from a Malaysian university, based on their results of a sleep quality screening instrument. The Pittsburg Sleep Quality Index (PSQI) differentiates sleep quality based on criteria including reliability, sensitivity, and specificity 16. Individuals who were pregnant, had a history of certain cardiac, liver, or kidney disorders, taking sleeping pills, taking supplements to enhance sleep quality, consuming over 10 cups of per day of coffee or tea (including green tea), or lactose intolerant were excluded from the study.

Based on the preliminary results of the PSQI, 42 subjects began the study with 39 completing it. The clinical trial was a 9-week randomized, double-blind, placebo-controlled, cross-over study, consisting of four weeks of intervention, via administration of either the milk-powder placebo or RLX2™ treatment, and one week of a “washout period” approved by the UTAR Scientific and Ethical Review Committee.

Pre-treatment and post-treatment PSQI questionnaire responses delivering a total score of subjective quality of sleep were recorded, as were blood pressure and heart measurements, salivary cortisol analysis, and electroencephalography (EEG). Paired t-tests were used to measure the differences between the results of the experimental and control groups; the tests were two-tailed with a designated level of significance at p<0.05.

Results indicated the following:

  • The experimental group demonstrated significant improvements in sleep duration and efficiency compared to the control group, based on decreased PSQI scores.
  • There were no significant changes demonstrated in systolic and diastolic blood pressures, heart rates, or salivary cortisol levels between the experimental and control groups.
  • The experimental group showed improvements in total alpha power and frontal alpha power for the EEG analysis compared to the control group.

The conclusions of the study suggest that the supplement, RLX2™, can help promote improved sleep quality as well as present anxiolytic effects.

Delimitations/limitations of the study include use of a convenience population from which samples were drawn (the academic staff of a Malaysian university), whose characteristics may not be representative of the population of Malaysia. The population size was small (< 100), thus increasing the risk of type II errors. The selection of low-fat milk powder as the placebo was noted; the study did not specify that the low-fat milk powder was evaluated to determine if it contained any bioactive variants of CTH.

Source: Thiagarajah, K., Chee, H.P., & Sit, N.W. (2022). Effect of Alpha-S1-Casein Tryptic Hydrolysate and L-Theanine on poor sleep quality: A double blind, randomized, placebo-controlled crossover trial. Nutrients, 14 (652). https://doi.org/10.3390/nu14030652

© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

Posted June 13, 2022.

Marlene Hollick, Ed.D., M.P.H., M.A., R.D, has decades of hands-on experience and academic expertise across a wide range of health and nutrition disciplines, including home care, hospitals, nursing homes, public schools, and higher education. Dr. Hollick earned her Ed.D. in Higher Education Leadership and Health Care Education from Nova Southeastern University, a Master of Public Health from New York University, and a Master of Arts in Food and Nutrition, also from NYU.  She is a Registered Dietitian, a Certified Dietitian/Nutritionist, and is currently enrolled in the post-graduate Science Writing program at Johns Hopkins University.

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