Brown Rice Bran and Its Potential Benefits for Mood and Sleep
Brown rice bran is the nutrient-rich outer layer of brown rice. It provides dietary fiber, B vitamins, magnesium, γ-oryzanol, and various antioxidant compounds. Although it is best known for its potential metabolic benefits, emerging research suggests that brown rice bran and rice bran extracts may also support mood and sleep.
Brown Rice Bran May Support Mood and Appetite Regulation
People with metabolic syndrome may experience changes in appetite-regulating hormones and an increased risk of depression. In an eight-week randomized controlled trial, researchers examined whether brown rice bran powder could improve mood, appetite control, insulin resistance, and cardiovascular risk indicators in adults with metabolic syndrome (1).
The study included 43 participants. Nineteen followed a standard healthy diet, while 24 followed the same diet with an additional 15 grams of brown rice bran powder per day. Mood was evaluated using the Beck Depression Inventory, while hunger, fullness, satiety, and desire to eat were measured using visual analogue scales. Researchers also measured serum ghrelin, insulin resistance, and seven indicators associated with atherosclerosis.
Compared with the standard-diet group, participants consuming brown rice bran experienced significant increases in ghrelin levels, fullness, and satiety. They also reported significantly less hunger and lower depression scores. In addition, brown rice bran reduced the metabolic score for insulin resistance and several cardiovascular risk indicators, including the atherogenic coefficient, Castelli Risk Index II, and cholesterol index (1).
These findings suggest that brown rice bran may support both psychological and metabolic well-being. However, because the study was small, open-label, and did not include a placebo, larger clinical trials are needed to confirm the results.
Rice Bran Extract May Improve Sleep
The potential sleep-promoting effects of rice bran were first observed in animal research. In mice, a rice bran extract supplement shortened the time needed to fall asleep and increased non-rapid eye movement, or NREM, sleep. Researchers proposed that these effects might involve inhibition of the histamine H1 receptor, which plays an important role in maintaining wakefulness.
Based on these findings, researchers conducted a two-week randomized, double-blind, placebo-controlled clinical trial involving 50 adults with sleep disturbances. Participants received either 1,000 mg of rice bran extract per day or a placebo (2).
Sleep was measured objectively using polysomnography. Participants also completed the Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, and Fatigue Severity Scale at the beginning and end of the study.
Compared with the placebo, rice bran extract produced several significant improvements:
Sleep latency decreased, meaning participants fell asleep faster.
Total sleep time increased.
Sleep efficiency—the percentage of time in bed spent asleep—improved.
The amount of stage 2 sleep increased.
Daytime sleepiness, measured by the Epworth Sleepiness Scale, decreased.
After researchers adjusted the results for caffeine intake, reductions in wakefulness after sleep onset, total wake time, and changes in delta-wave activity showed favorable trends but did not reach statistical significance. No serious adverse events were reported in either group (2).
These results suggest that rice bran extract may improve sleep continuity by helping people fall asleep faster, sleep longer, and spend a greater proportion of their time in bed asleep.
Summary
Early clinical research suggests that brown rice bran powder may reduce depression scores and improve appetite regulation in people with metabolic syndrome. A concentrated rice bran extract may also improve sleep onset, total sleep time, sleep efficiency, stage 2 sleep, and daytime sleepiness in adults with disturbed sleep.
However, brown rice bran powder and concentrated rice bran extract are different preparations and should not be considered interchangeable. The existing studies were also small and relatively short. More extensive clinical research is needed to determine their long-term benefits, optimal doses, and possible roles in supporting mood and sleep.
References
Mahdavi-Roshan M, Dashti F, Zamani E, et al. Effects of brown rice bran on appetite and depression in metabolic syndrome: a secondary analysis of an open-label randomised controlled trial. British Journal of Nutrition. 2025;134(12):1046–1056. PubMed
Um MY, Yang H, Han JK, et al. Rice bran extract supplement improves sleep efficiency and sleep onset in adults with sleep disturbance: a randomized, double-blind, placebo-controlled, polysomnographic study. Scientific Reports. 2019;9:12339. PubMed
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