A new study found that eating a small handful of walnuts every day might improve your sleep. Researchers gave 76 young adults either 40 grams of walnuts (about a quarter cup) or no nuts to eat for 8 weeks. The people who ate walnuts fell asleep faster, slept better overall, and felt less sleepy during the day. The study suggests walnuts contain natural compounds that help your body prepare for sleep. While these results are promising, more research is needed to fully understand how walnuts work their sleep magic.

The Quick Take

  • What they studied: Does eating walnuts every day help people sleep better and increase natural sleep chemicals in their bodies?
  • Who participated: 76 young adults (average age 24 years old, mostly women) who ate either 40 grams of walnuts daily or no nuts for 8 weeks
  • Key finding: People who ate walnuts fell asleep about 9 minutes faster, had better overall sleep quality, and felt less tired during the day compared to when they didn’t eat walnuts
  • What it means for you: Adding a small handful of walnuts to your dinner might be a simple, natural way to improve your sleep—but it’s not a cure-all, and individual results may vary

The Research Details

This was a randomized crossover trial, which means researchers split participants into two groups that switched roles halfway through. One group ate 40 grams of walnuts (about a quarter cup) with dinner every night for 8 weeks, while the other group ate no nuts. Then they switched: the walnut group stopped eating walnuts, and the non-walnut group started eating them. This design is powerful because each person serves as their own comparison, showing how walnuts specifically affected their sleep.

Researchers measured sleep in two ways. First, they collected urine samples in the evening (8 PM to 11 PM) and at night (11 PM to 7 AM) to measure a chemical called 6-SMT, which is a breakdown product of melatonin—your body’s natural sleep hormone. Second, they tracked actual sleep quality using standard sleep measurements like how long it takes to fall asleep, how many times you wake up, and how much of your time in bed you actually spend sleeping.

The researchers also tested the walnuts themselves to measure exactly how much of sleep-promoting compounds they contained. This careful approach helps explain why the walnuts might have worked.

This study design is important because it eliminates many confusing factors. By having people serve as their own control group, researchers could see the direct effect of walnuts without other lifestyle differences getting in the way. The crossover design is considered one of the strongest ways to test whether a food actually affects health.

Strengths: The study used a randomized design, measured actual sleep chemicals in urine (objective data), and had participants track sleep quality. The sample size of 76 is reasonable for this type of study. Limitations: The study only included young adults (mostly women), so results may not apply to older people or men. The study was ‘open-label,’ meaning participants knew whether they were eating walnuts, which could influence how they felt. The study lasted only 8 weeks, so we don’t know if benefits continue long-term.

What the Results Show

The main finding was clear: eating walnuts increased a sleep-related chemical in the body. Evening urine samples showed significantly higher levels of 6-SMT (a melatonin breakdown product) when people ate walnuts compared to when they didn’t. This is important because it suggests walnuts contain compounds that boost your body’s natural sleep system.

Sleep quality improved noticeably. People fell asleep about 9 minutes faster when eating walnuts—this might not sound like much, but it was statistically significant and consistent across the group. More importantly, their overall sleep quality improved, meaning they slept more soundly and woke up less often during the night.

Daytime sleepiness decreased significantly. Using a standard sleepiness scale, people reported feeling less tired and drowsy during the day when they ate walnuts. This suggests the walnuts didn’t just help them sleep at night—they also felt more alert and energetic the next day.

The connection between the sleep chemical and sleep quality was real. When researchers looked at the relationship between higher 6-SMT levels and sleep improvements, they found a strong connection, suggesting the chemical increase actually caused the sleep improvements.

The study found that walnuts contain meaningful amounts of tryptophan and melatonin—two compounds known to support sleep. Tryptophan is an amino acid your body uses to make serotonin and melatonin, while melatonin directly signals your body that it’s time to sleep. The presence of these compounds in walnuts helps explain the mechanism behind the sleep improvements.

Previous research has suggested that nuts contain sleep-promoting compounds, but this is one of the first rigorous studies to test walnuts specifically and measure actual sleep chemicals in the body. Other studies have looked at melatonin supplements or other foods, but this research provides stronger evidence that a whole food (walnuts) can meaningfully affect sleep through natural compounds.

The study only included young adults with an average age of 24, so we don’t know if walnuts help older adults or teenagers sleep better. The group was 85% women, so results may not apply equally to men. The study lasted only 8 weeks, so we don’t know if the benefits continue if you eat walnuts for months or years. Because participants knew they were eating walnuts, they might have expected to sleep better, which could have influenced their results. The study didn’t measure whether other factors (like exercise, stress, or caffeine) affected the results.

The Bottom Line

If you have trouble sleeping, adding a small handful of walnuts (about 40 grams or a quarter cup) to your dinner might help. This is a low-risk, natural approach worth trying. However, walnuts are not a replacement for good sleep habits like keeping a consistent bedtime, avoiding screens before bed, or managing stress. If you have serious sleep problems, talk to a doctor. Confidence level: Moderate—this study shows promise, but more research in different age groups is needed.

Young adults who struggle with falling asleep or feel tired during the day might benefit most from this finding. People who prefer natural approaches to sleep support may find walnuts appealing. However, if you’re allergic to tree nuts or have a medical condition affecting sleep, talk to your doctor first. This study doesn’t tell us yet whether walnuts help older adults, teenagers, or people with serious sleep disorders.

Based on this study, you might notice improvements in how quickly you fall asleep within a few weeks of eating walnuts daily. The study lasted 8 weeks, so that’s a reasonable timeframe to give it a fair try. Some people might notice benefits sooner, while others might take longer.

Want to Apply This Research?

  • Track your sleep latency (time to fall asleep) and overall sleep quality rating (1-10 scale) each morning for 2 weeks before adding walnuts, then continue tracking for 8 weeks while eating 40g of walnuts daily with dinner. Compare the two periods to see if your sleep improved.
  • Set a daily reminder to eat a quarter cup of walnuts with dinner. You could add them to salads, yogurt, oatmeal, or eat them plain. Log each time you eat them in the app to build the habit and track consistency.
  • Use the app to create a simple sleep journal: record bedtime, wake time, number of awakenings, and a sleep quality rating each morning. After 8 weeks, review your data to see if there’s a pattern showing improvement. If you see benefits, continue the habit; if not, you’ll have clear data to discuss with a healthcare provider.

This research suggests walnuts may help improve sleep in young adults, but it is not medical advice. Walnuts are not a treatment for sleep disorders or insomnia. If you have persistent sleep problems, consult a healthcare provider before making dietary changes. This study was conducted in young adults and may not apply to children, older adults, or people with certain health conditions. Always talk to your doctor before significantly changing your diet, especially if you take medications, have allergies, or have existing health conditions. Individual results may vary.