Eating walnuts before bed may improve sleep quality, study finds
A new study suggests that eating a handful of walnuts in the evening could help people fall asleep faster and improve overall sleep quality
Walnuts may help improve sleep when eaten as part of an evening routine, according to a new study that found the nutrient-rich nuts were associated with better sleep quality and higher melatonin production.
Researchers followed 76 adults aged 20 to 35 over an 18-week period to examine whether daily walnut consumption affected sleep. Participants alternated between eating 40 grams of walnuts with dinner and avoiding walnuts altogether, allowing researchers to compare sleep patterns during both phases.
The study found that participants produced more melatonin in the evening when they consumed walnuts. They also fell asleep faster, reported better overall sleep quality and experienced less daytime sleepiness.
Sleep quality was measured using wearable wrist trackers and assessments that evaluated how long it took participants to fall asleep, how efficiently they slept, the number of nighttime awakenings and the amount of time spent awake after initially falling asleep.
Why walnuts may support sleep
Researchers believe the effects may be linked to walnuts' natural composition.
Analysis of the nuts found that each serving contained approximately 84.6 milligrams of tryptophan, an amino acid the body uses to produce serotonin and melatonin. Walnuts also contained measurable amounts of melatonin, the hormone responsible for regulating the body's sleep-wake cycle.
According to behavioural sleep medicine psychologist Daniella Marchetti, tryptophan serves as the foundation for producing both serotonin and melatonin, two compounds closely tied to healthy sleep patterns.
Melatonin levels naturally rise in the evening to signal that it is time for sleep. Consuming foods that contain the hormone may help reinforce that process and support the body's preparation for rest.
Researchers also noted that walnuts contain a favourable ratio of tryptophan to competing amino acids, potentially making it easier for tryptophan to reach the brain and contribute to melatonin production.
Findings come with limitations
While the results suggest walnuts could be a useful addition to a sleep-friendly diet, experts cautioned against viewing them as a treatment for insomnia or other sleep disorders.
The study involved a relatively small group of participants and was funded by the California Walnut Commission, though researchers said the organisation did not influence the study's design or conclusions.
Participants were also aware of whether they were eating walnuts, raising the possibility that expectations may have influenced some of the reported benefits. In addition, all participants followed a Mediterranean-style diet during the trial, making it difficult to isolate the effects of walnuts alone.
Still, the findings add to growing evidence that certain foods may play a role in supporting sleep.
Experts suggest consuming about 30 to 40 grams of walnuts — roughly a small handful — after dinner or as an evening snack. Because melatonin levels may take several hours to increase, eating walnuts earlier in the evening could provide the greatest benefit.
While more research is needed, the study suggests that a simple dietary change may help support better sleep quality and overall rest.
Note to readers: This article is for informational purposes only and not a substitute for professional medical advice. Always seek the advice of your doctor with any questions about a medical condition.
