The Role of Peanuts and Tree Nuts in Improving Diet and Sleep Quality: A Pilot Study and Literature Review
Background: Peanuts and tree nuts are nutrient-dense foods associated with improved diet quality and reduced chronic disease risk. Diet quality and sleep are interrelated, but the relationship between nut consumption and sleep quality remains understudied, particularly among young adults. Objective: This study examined peanut and tree nut consumption, diet quality, and sleep quality in undergraduate students. Existing clinical trials on nut intake and sleep outcomes in healthy adults were reviewed. Methods: A pilot study recruited 46 undergraduates to complete three 24 h dietary recalls and self-report sleep quality. Recall days were categorized as containing nuts or no nuts. Diet quality was assessed using the Healthy Eating Index-2020 (HEI). A literature search of PubMed identified human clinical trials testing nut intake with sleep-related outcomes. Results: Sixteen percent of the 139 recall days contained nuts. Mean HEI scores were greater on days that contained nuts (64.9 ± 2.3) versus nut-free days (45.4 ± 1.1; p < 0.0001). Scores for total fruit, whole fruit, total protein, sea and plant protein, sodium, and refined grains were greater on nut-containing days (p < 0.05 for all). Participants reported better sleep on days following nut consumption (p = 0.04). From the literature search, four randomized controlled trials (RCTs) were identified with results varying by nut type, dosage, timing, and participants. Conclusions: The positive association observed in this pilot study between nut intake and improved diet quality, along with a modest link to better sleep quality, suggests that incorporating nuts regularly into the diet may help enhance overall dietary habits and contribute to improved sleep. The present trials suggest nut intake may improve sleep quality, but significant heterogeneity highlights the need for RCTs with objective sleep outcomes.
https://doi.org/10.3390/nu18040579
Legumes and nuts intake in relation to sleep duration and quality, oxidative stress and inflammation in Iranian adults
Optimal sleep, as a vital part of life, has significant impacts on various aspects of social health. Dietary intake, particularly through its influence on oxidative stress and inflammation, is a crucial modifiable factor for sleep health. Given the high prevalence of sleep disorders in the Iranian population, we investigated the association of the intake of legumes and nuts with their sleep quality and quantity and inflammation and oxidative stress levels. Our cross-sectional study comprised 535 participants (46% female, aged 20-65 years), selected via a multistage cluster random sampling approach. Their dietary intake was evaluated using a validated food frequency questionnaire. Sleep metrics were assessed through the Pittsburgh Sleep Quality Index. Fasting blood samples were gathered to assess the levels of oxidative stress and inflammation biomarkers. Our analyses revealed significant negative relations between the consumption of legumes and nuts and the odds of short sleep (fully adjusted OR = 0.56, 95% CI: 0.33-0.94) and poor sleep quality (fully adjusted OR = 0.51, 95% CI: 0.31-0.85); these associations were in a dose-response manner and more pronounced in females. Moreover, a U-shaped association was observed between glutathione peroxidase levels and the odds of poor sleep quality. These findings highlighted the significant association of enhancing the consumption of legumes and nuts with sleep quality and quantity improvement among Iranian adults.
https://doi.org/10.1039/d5fo04053a
Daily walnut consumption increases 6-sulfatoxymelatonin urinary levels and can improve sleep quality: a randomized crossover trial
We aimed to study the potential impact of daily consumption of walnuts on urinary 6-sulphatoxymelatonin (6-SMT) levels and sleep quality parameters. We conducted an open-label randomized crossover trial (NCT04799821) in 76 young adults (24.1 ± 3.4 years; 85.5% women) who either ingested 40 g of walnuts daily during dinner (intervention) or refrained from eating walnuts or any other nuts (control) for 8 weeks, with a 2-week washout period. Outcome variables included the determination of 6-SMT in urine samples collected in two consecutive periods: evening (from 20:00 to 23:00) and nighttime (from 23:00 to 07:00), the measurement of sleep quality parameters (latency, wake after sleep onset, awakenings, and efficiency) and daytime sleepiness (Epworth Sleepiness Scale). Tryptophan and melatonin contents of the walnuts used for the intervention were quantified by high-performance liquid chromatography. The 8-week walnut intervention significantly increased evening urinary 6-SMT concentrations (p = 0.029) and improved sleep latency (p = 0.001), while no differences were found between the baseline and control conditions. Likewise, the walnut intervention resulted in increased global sleep quality (p = 0.002) and lower daytime sleepiness (p = 0.002). Partial correlation analyses indicated that during the intervention, evening urinary 6-SMT concentrations were significantly associated with higher sleep efficiency (p = 0.026) and an improved global sleep quality (p = 0.006). Our findings highlight the potential of walnuts as sleep-promoting foods among young adults. Specifically, we demonstrated that a daily serving of 40 g of walnuts increases urinary 6-SMT levels, reduces sleep latency, and improves global sleep quality. Further research is needed to fully understand the underlying mechanisms involved in the diet-sleep association.
https://doi.org/10.1039/d5fo00971e