Adults with self-reported sleep problems who ate two green kiwifruits an hour before bed fell asleep faster and stayed asleep longer. The finding comes from a small four-week study published in the Asia Pacific Journal of Clinical Nutrition that tracked 24 adults before and after adding the fruit.
The participants, most of them women aged 20 to 55, followed the routine nightly. Sleep-onset latency fell by roughly 35 percent, and total sleep time rose by about 13 percent.
Subjective sleep quality scores also improved, and time awake after falling asleep dropped by around 29 percent. The study had no placebo group, so some of the effect could reflect expectation rather than the fruit itself.
The researchers pointed to compounds in kiwifruit that may help explain the effect. Kiwi contains serotonin and antioxidants, both linked to sleep regulation. Serotonin is a precursor to melatonin, the hormone that governs the sleep-wake cycle.
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What a newer trial added
A 2023 crossover trial in Frontiers in Nutrition tested fresh and freeze-dried kiwifruit against a water control in 24 healthy young men, half of them poor sleepers. Both kiwifruit preparations raised urinary concentrations of 5-HIAA, the main breakdown product of serotonin.
Poor sleepers who ate dried kiwifruit reported easier awakenings, and mood measures of vigor also improved. The authors concluded that kiwifruit with an evening meal was associated with better sleep and mood, possibly through changes in serotonin metabolism.
The trial was small and short-term. It does not prove that kiwis cause better sleep, and the melatonin metabolite aMT6s showed no significant change.
The blood-pressure trial
Sleep is not the only outcome researchers have studied. An eight-week randomized controlled trial in Blood Pressure put 118 adults with high-normal blood pressure or stage 1 hypertension on either three kiwifruits or one apple a day.
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At the end of the eight weeks, 24-hour ambulatory blood pressure was lower in the kiwifruit group. The between-group difference was 3.6 mmHg for systolic and 1.9 mmHg for diastolic pressure, in favor of kiwifruit.
That is a modest shift, but at a population level even a few mmHg matters. The researchers noted that kiwifruit contains bioactive substances that may support endothelial function, the health of the inner lining of blood vessels.
What this means in practice
None of these trials is large, and the sleep studies leaned on subjective measures. Kiwifruit is not a substitute for a sleep evaluation or blood-pressure treatment, and anyone with persistent insomnia or hypertension should talk to their doctor.
Still, the pattern that keeps showing up is unusual for a common supermarket fruit. Two green kiwis an hour before bed, or three across the day, has been tested in real clinical trials and linked to measurable, if modest, changes.
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For readers looking for small dietary tweaks, kiwifruit is inexpensive and easy to add to an evening meal. The trials so far are small, but the direction of the effect has been consistent.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.