You have probably seen the claim pop up on your feed. Eat a handful of pistachios before bed, the headline promises, and you will sleep better. It sounds too tidy, and it leaves most of us wondering if anything in the kitchen can actually move the needle.
A review published online in September 2026 in Nutrition Research Reviews took stock of what pistachios contain and whether those compounds plausibly help with sleep. It was led by researchers at Columbia University in New York.
The chemistry is there. The trial that would prove it works in real sleepers is still missing.
A one-ounce serving, about 28 grams or a small handful, delivers around 71 milligrams of tryptophan. That amino acid is the raw material the body uses to make serotonin and then melatonin, the hormone that signals the brain it is time for sleep.
Also read: Girls who took this supplement for a year built measurably more bone than those who didn't
The same handful also carries a small amount of a plant form of melatonin itself, known as phytomelatonin. The amount varies widely from one measurement to the next. Some reports put it near 18.7 micrograms per serving, while others log it as low as 0.074 micrograms.
Pistachios also bring magnesium and vitamin B6. The body uses both as helpers in the chain reaction that produces melatonin. The nuts carry fiber and polyphenols too, which feed gut bacteria that in turn influence sleep signaling, the review notes.
What the Columbia review actually concluded
Senior author Marie-Pierre St-Onge made the case in a statement issued with the paper. "Pistachios are compelling for sleep research because they bring together several nutrients and plant compounds connected to sleep physiology within one whole food," she said.
She directs the Center of Excellence for Sleep and Circadian Research at Columbia University Irving Medical Center.
Also read: Study of 147,000 people reveals the ideal amount of strength training for a longer life
That is a long way from saying pistachios improve sleep. The authors are careful on this point. Having the right ingredients in a food is not the same as proving the food changes how long or how well people sleep.
The review calls for randomized controlled trials that directly measure sleep after a pistachio intervention. The Columbia team says human trials of whole pistachios are now underway.
Where pistachios sit next to a melatonin pill
Many people reach for a melatonin supplement instead of a food. That market has its own quality problem.
The National Center for Complementary and Integrative Health, part of the NIH, reports that for most melatonin products tested, the amount in the bottle did not match the amount on the label.
Also read: How many hours of sleep do you really need? Your target, sorted by age
The agency cites a 2023 analysis of 25 over-the-counter melatonin gummies. Most were inaccurately labeled. Measured melatonin ranged from well below the stated dose to more than three times above it.
Reported side effects in short-term studies include headache, dizziness, nausea and daytime sleepiness.
Pistachios do not sidestep every question. Reviewing one nutrient on its own is a different test from eating the whole food. Welltica's look at magnesium supplements and sleep found the evidence still mixed.
The review was funded by American Pistachio Growers and the National Institutes of Health. Human clinical trials testing whole pistachios on sleep outcomes are in progress, according to the Columbia team.
Also read: The word that is quietly costing women's health brands their reach online
Also read: What should you eat first on your plate? New study reveals the answer
This article is made and published by Jesper Bengtson, who may have used AI in the preparation.