You don’t sleep well? Have a go at these nuts.
When it comes to brain-nourishing foods, walnuts are definitely on the list. With their wrinkled kernel resembling the human brain, they are packed with a variety of nutrients that benefit brain health.
A new study has found that besides boosting brain function, walnuts also help improve sleep quality.Having some walnuts with dinner may help you sleep better.
Recently, a research team from the University of Barcelona, Spain, published a study in the journal Food & Function. The findings show that eating walnuts at dinner can regulate the body’s melatonin metabolism, thereby significantly improving sleep quality and aiding sleep.
In the experiment, participants consumed 40 grams of walnuts daily with dinner for 8 consecutive weeks. Compared with the control group, the walnut group showed a shorter sleep onset latency, higher overall sleep quality scores, reduced daytime sleepiness, and a 0.72% increase in sleep efficiency.
Researchers explained that walnuts are rich in tryptophan, a precursor of melatonin that promotes melatonin synthesis. In addition, the plant-based melatonin naturally present in walnuts also helps enhance sleep quality.
Nutritional Breakdown of Walnuts
Zuo Xiaoxia, Director of the Nutrition Department at the Eighth Medical Center of Chinese PLA General Hospital, stated that walnuts are like a natural nutrition treasure trove, containing abundant ingredients beneficial to cardiovascular health.
1. Unsaturated Fats
Walnuts are predominantly rich in unsaturated fatty acids, which help regulate blood lipids and maintain blood vessel elasticity, benefiting cardiovascular health. Meanwhile, the phospholipids in walnut kernels are highly beneficial to brain tissue, earning walnuts the reputation of natural brain gold.
2. Dietary Fiber
It promotes gastrointestinal peristalsis, prevents constipation, and enhances satiety.
3. Amino Acids
Previous studies indicate that walnut protein contains 18 kinds of amino acids, including all 8 essential amino acids. Its composition is close to the human amino acid pattern, making it beneficial for growth and development.
4. Vitamins & Minerals
Walnuts are high in vitamin E, which provides antioxidant and anti-aging effects and boosts immunity. The zinc in walnuts is a key component of the pituitary gland and helps assist in the management of hypertension and cardiovascular diseases.
5. Active Ingredients
Walnuts are abundant in phenolic compounds. Intake of polyphenols helps reduce inflammatory responses in brain cells and improve neural signal transmission. It is linked to better memory, cognitive flexibility, information processing speed and overall cognitive function, and helps prevent cognitive decline.
A 2025 study published in the U.S. journal Cancer Prevention Research found that regular walnut consumption reduces inflammation and lowers the risk of colon cancer, thanks to its rich polyphenolic compounds.
Four Principles to Gain Full Health Benefits from Walnuts
Fan Zhihong, Professor at the College of Food Science and Nutritional Engineering, China Agricultural University, pointed out that to fully enjoy the antioxidant benefits of walnuts, four conditions should be met:
Walnuts must be fresh without fat oxidation.
Choose original-flavor walnuts with no added salt or sugar.
Eat freshly shelled walnuts directly, or lightly roast them only. Avoid deep-frying or over-baking. Heating above 120℃ will produce more pro-inflammatory substances as temperature rises and heating time lengthens.
Do not peel off the thin brown skin on walnut kernels, as most antioxidant nutrients are concentrated in this skin.
According to China’s Dietary Guidelines, healthy adults are recommended to eat 10 grams of nut kernels per day (about 1 to 2 walnuts). A daily intake of 25–28 grams is also acceptable, but corresponding calorie intake from other foods should be reduced. For example, replace snacks such as cookies, potato chips and beef jerky with walnuts, or choose steaming and boiling instead of stir-frying in daily cooking.