May 22, 2025, 1:38 pm | Read time: 5 minutes
Like many other fruits, kiwis are rich in vitamins and minerals. One hundred grams provide about 50 percent of the daily requirement for vitamin C. They also contain significant amounts of vitamin E, potassium, and vitamin K. Additionally, this berry fruit, originally from East Asia, is relatively high in fiber, promoting healthy digestion. However, few people know that kiwis also appear to affect sleep. FITBOOK Editor-in-Chief Nuno Alves has examined the research in detail and shares his own experiences.
When I first heard about the potential effects of kiwis on sleep in a podcast, I could hardly believe it. Two kiwis before bedtime are supposed to noticeably improve sleep? That sounded almost too good to be true. So, I started looking for studies that examined the connection between kiwi consumption and sleep quality. Indeed, there are several. However, the problem is that some studies were partially funded or supported by kiwi-producing companies.
Overview
What Studies Say About the Effects of Kiwis on Sleep
The first study specifically examining the influence of kiwis on sleep was published in 2011 and was partially funded by Zespri, a kiwi distributor.1
Scientists at Taipei University examined whether the regular consumption of the fruit could improve sleep quality in 24 adults with self-reported problems. For four weeks, the participants ate two kiwis every evening. Sleep parameters were collected using questionnaires, a sleep diary, and a special wristband. The result: Participants fell asleep 35.4 percent faster on average, reported 28.9 percent fewer nighttime awakenings, and extended their total sleep duration by 13.4 percent. Sleep efficiency also increased by 5.41 percent. The overall sleep quality score improved significantly. The objective measurements from the wristband confirmed an increase in sleep duration by 16.9 percent and efficiency by 2.38 percent. However, there were no significant changes in sleep onset time and nighttime wakefulness.
Another study from New Zealand, which confirms the effect, was also partially supported by Zespri.2 The placebo-controlled crossover study from 2023 aimed to find out how kiwi affects the sleep of 24 young men. Twelve were good sleepers, and twelve were poor sleepers. Participants ate either two fresh kiwis, a freeze-dried kiwi powder mix (with skin), or just water in the evening. In addition to sleep, mood and certain urine values were analyzed. The result: Consuming kiwi helped participants get out of bed more easily and feel more awake in the morning. The effect was even stronger with freeze-dried kiwis. Additionally, after consuming fresh or dried kiwi, the level of a serotonin breakdown product (5-HIAA) in the urine increased significantly—an indication that kiwi indeed has a biochemical effect.
Independent Studies Also Report Positive Effects of Kiwis on Sleep
Although the studies mentioned above provide interesting insights, doubts about their objectivity remain due to the support from a kiwi distributor. However, there are also independent investigations. In a randomized study from Norway in 2017, researchers wanted to know the influence of kiwis on the sleep of people with chronic insomnia symptoms.3 For this common sleep disorder, conventional therapies such as cognitive behavioral therapy are not always sufficient. Seventy-four students ate 130 grams of kiwis or—as a control fruit—pears daily for four weeks, each one hour before bedtime. The evaluation was based on sleep logs, actigraphy data (movement measurements via wristband for objective sleep assessment), and established questionnaires.
Result: While objective sleep parameters remained unchanged, subjective sleep quality and daytime well-being improved significantly in the kiwi group. The authors conclude that kiwis may have sleep-promoting properties—especially on a subjective level. However, a placebo effect cannot be ruled out.
In another study, scientists in 2023 analyzed for the first time the influence of kiwis on sleep and recovery in elite athletes—a group particularly prone to sleep problems due to late training sessions, competitions, and frequent travel.4
Fifteen national team athletes, including sailors and middle-distance runners, consumed two green kiwis every evening for four weeks, each one hour before bedtime. The results showed clinically significant improvements:
- significantly improved sleep quality
- total sleep duration approached the recommended range for athletes (8 to 10 hours)
- increased sleep efficiency at previously borderline levels
- reduced nighttime awakenings
- less wakefulness after falling asleep
- less morning fatigue
- reduced general stress perception
- reduced sports-related stress perception
Although the results were based solely on self-reports—which means errors cannot be ruled out—the authors emphasize the practicality of this simple, diet-based measure.
Eating Before Bed: The Surprising Effects of Kiwis
How Healthy Are Psyllium Husks Really?
“My Tips for an Effective Home Workout You Can Stick With”
Possible Reasons for the Positive Effects of Kiwis on Sleep
A possible explanation for the sleep-promoting effects is provided by the New Zealand researchers, where the independence of the study is at least questionable. Nonetheless interesting: The scientists suspect a connection with serotonin metabolism. Serotonin—often referred to as the happiness hormone—plays an important role in sleep regulation and is present in significant amounts in kiwis. Additionally, the berry fruit naturally contains plenty of melatonin, which is also crucial in regulating the sleep-wake cycle. One hundred grams contains about 2.4 milligrams—a relevant amount that exceeds the content of many over-the-counter supplements.
My Experiences with Kiwi
“Of course, I also tried how consuming one or two kiwis about an hour before bedtime affects sleep. My experience after several weeks: My sleep is on average a bit better and deeper, and I feel I wake up less frequently at night. This subjective impression is partially supported by the measurements from my sleep tracker ring. Is this always the case? No. Even after consuming kiwis, I’ve had mixed nights. This shows that sleep quality depends on many factors and is not influenced solely by individual measures or foods.”
Interesting: Extreme athlete and adventurer Jonas Deichmann, who completed 120 Ironman-distance triathlons in a row last year, setting a world record, swears by kiwi for better sleep. In an interview with me, Jonas said: “This is confirmed by studies.” During his world record project “Challenge 120,” he ate two kiwis 45 minutes before bedtime to promote the most restful sleep possible.
One thing can be said: A kiwi in the evening doesn’t hurt—and is one of the healthier options compared to many sleep aids that are taken.