Kiwi before bed: two small studies, read closely
Two kiwis an hour before bed has become one of the internet's favorite sleep tips. It rests mainly on one small study from 2011. Here is what that study did, what it could not rule out, and what has been tested since.
contentsWhere the tip comes from
Key points
- The tip comes from a 2011 study of 24 adults who ate two kiwifruit an hour before bed for 4 weeks.
- Diary sleep improved a lot. A wrist sensor confirmed longer sleep, but not faster sleep onset.
- There was no control group, so expectation could explain part of the change.
- A 2023 trial in 24 young men found some morning benefits after a single evening serving.
- Both studies were small. Kiwi is a cheap, low-risk thing to try, not a substitute for proper help.
Where the tip comes from
Almost every “eat kiwi for sleep” post traces back to one study. In 2011, researchers in Taiwan asked 24 adults with self-reported sleep problems to eat two kiwifruit an hour before bed, every night for four weeks. They tracked sleep with diaries, a questionnaire and a wrist-worn sensor.[47]
What changed
chart · total sleep time, before and after 4 weeks
Both the diary and the wrist sensor showed longer nights
Diary, start
355 minDiary, week 4
395 minWrist sensor, start
362 minWrist sensor, week 4
417 min
In their diaries, people reported falling asleep in about 20 minutes instead of 34. The wrist sensor told a more mixed story: total sleep and sleep efficiency rose, but the drops in time to fall asleep and time awake in the night were not statistically significant.[47]
The missing control group
Here is the catch. Everyone ate kiwi. Nobody ate a placebo fruit or carried on as normal for comparison. The authors said themselves that they could not rule out an expectation effect.[47]
Other limits are worth knowing too. 22 of the 24 were women, sleep problems were self-reported rather than diagnosed, and the fruit was supplied, and the study supported, by a kiwifruit company.[47] None of that makes the result false. It makes it a starting point.
A newer trial
In 2023, a New Zealand team ran a better-controlled test. 24 young men, half good sleepers and half poor sleepers, had fresh kiwi, dried kiwi powder or water with an evening meal, in random order.[48]
After the dried kiwi, people reported less morning sleepiness, more alertness on waking and more vigor than after water. Fresh kiwi mostly produced trends that fell just short of significance.[48] That is a single-serving, single-blind study in men only, so it adds a little support rather than settling the question.
Is it worth trying?
As a habit, two kiwis in the evening costs little and carries little risk for most people. As a fix for ongoing insomnia, the evidence is nowhere near strong enough. If bad nights are affecting your days, a doctor is the right next step, ideally with a week or two of sleep notes in hand.[3]
Our sleep diary guide makes that easy, and the sleepy girl mocktail piece checks another food trend the same way.
Small studies, honestly read.
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Sources
- Lin et al., 2011. Effect of kiwifruit consumption on sleep quality in adults with sleep problems. Asia Pacific Journal of Clinical Nutrition.
- Kanon et al., 2023. Acute effects of fresh versus dried Hayward green kiwifruit on sleep quality, mood, and sleep-related urinary metabolites in healthy young men with good and poor sleep quality. Frontiers in Nutrition.
- NHLBI, 2022. Insomnia: Diagnosis. National Heart, Lung, and Blood Institute (NIH).
This article is educational and isn’t medical advice. It was written and checked by the UNWIRE™ editorial team; no clinician has reviewed it yet. UNWIRE™ is a nutrition company, and this article does not describe any product.
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