The effects of a sleep/recovery supplement: 'Night Time Recharge' on sleep parameters in young adults

Nutritional Interventions to Improve Sleep in Team-Sport Athletes: A Narrative Review

Athletes often experience sleep disturbances and poor sleep as a consequence of extended travel, the timing of training and competition (i.e., early morning or evening), and muscle soreness. Nutrition plays a vital role in sports performance and recovery, and a variety of foods, beverages, and supplements purportedly have the capacity to improve sleep quality and quantity. Here, we review and discuss relevant studies regarding nutrition, foods, supplements, and beverages that may improve sleep quality and quantity. Our narrative review was supported by a semi-systematic approach to article searching, and specific inclusion and exclusion criteria, such that articles reviewed were relevant to athletes and sporting environments. Six databases—PubMed, Scopus, CINAHL, EMBASE, SPORTDiscus, and Google Scholar—were searched for initial studies of interest from inception to November 2020. Given the paucity of sleep nutrition research in the athlete population, we expanded our inclusion criteria to include studies that reported the outcomes of nutritional interventions to improve sleep in otherwise healthy adults. Carbohydrate ingestion to improve sleep parameters is inconclusive, although high glycemic index foods appear to have small benefits. Tart cherry juice can promote sleep quantity, herbal supplements can enhance sleep quality, while kiwifruit and protein interventions have been shown to improve both sleep quality and quantity. Nutritional interventions are an effective way to improve sleep quality and quantity, although further research is needed to determine the appropriate dose, source, and timing in relation to training, travel, and competition requirements.

Efficacy of dietary supplements on improving sleep quality: a systematic review and meta-analysis

PURPOSE

Different dietary supplements aimed at improving sleep quality are available on the market, but there has not been a comprehensive review to evaluate the efficacy of these dietary supplements on subjective sleep quality. We aimed to summarise up-to-date research evidence and to identify the types of dietary supplement that improve subjective sleep quality.

METHODS

Multiple databases (Ovid Emcare, Ovid MEDLINE (R) and Epub Ahead of Print, In-Process & Other Non-Indexed Citations and APA PsycInfo) were used for searching papers published until August 2020. The changes in sleep quality indices, intervention duration and sample size were extracted from every paper. To analyse the effect of dietary supplements on sleep quality, a random effects model with mean difference (MD) and 95% CI was adopted. The heterogeneity across studies was measured by I² statistics. The quality of included studies was evaluated by Cochrane's risk of bias tool.

RESULTS

Thirty-one randomised controlled trials of dietary supplements were included. Subjective sleep quality was significantly improved by supplementation of amino acids (MD -1.27, 95% CI -2.35 to -0.20; I²=0%), melatonin (MD -1.21, 95% CI -2.17 to -0.24; I²=79%) and vitamin D (MD -1.63, 95% CI -3.15 to -0.10; I²=85%). Although not all studies provided adequate data for meta-analysis, we also discussed how magnesium, zinc, resveratrol and nitrate supplementation may improve sleep quality.

CONCLUSIONS

Amino acids, vitamin D and melatonin supplements were significantly beneficial to improve sleep quality. However, high heterogeneity and wide confidence levels were observed in vitamin D and melatonin. Further research on the effect of magnesium, zinc, resveratrol and nitrate supplementation on improving sleep quality is required.

Characteristics, Preferences and Health Care Utilization in Patients Using a Dietary Supplement for Improving Sleeping Disturbances: Results from an Explorative Online Survey

PURPOSE

Sleeping disturbances are highly prevalent in the general population, and pharmacological drug treatment harbours the risk of serious side effects. Many affected persons use dietary supplements for self-treating their symptoms, but little is known about the specific characteristics and preferences of these patients. Even less evidence exists about the consequences of a specific dietary supplement usage on health care utilization. The aim of this study was to explore characteristics, preferences and the impact on health care utilization in patients using a specific over-the-counter dietary supplement, which is promoted for improving sleeping disturbances.

PATIENTS AND METHODS

We conducted a structured survey and invited a sample of 297 customers of a specific dietary supplement to participate. The survey was open between June and September 2020. Participants were invited by email. All participants accepted an informed consent.

RESULTS

A total of 127 customers participated in the survey (participation rate: 42.8%). Of them, 87.7% were female and the mean age 50.5 years. Participants reported an overall good improvement of symptoms (7.66 on a ten-point Likert-scale) and showed a strong belief in the effectiveness of supplements in general; 67% of participants reported that the intake led to fever physician encounters, and 48.3% reported that they could stop the intake of other pharmaceutical sleeping drugs.

CONCLUSION

A significant proportion of participants reported a substantial reduction in pharmaceutical drug use and health care utilization. While these self-reports lack an adequate control, they are still real consumer experiences, and the large beneficial effects - whether placebo or not - explain the popularity of such supplements and their therapeutic potential in sleeping disorders.