Does Kiwifruit Improve Sleep Quality? What Four Studies Suggest

• There are reports that consuming kiwifruit has a positive effect on sleep quality.
• The evidence score is 65, and reliability is moderate.
• This information is relevant to people who have sleep concerns or who have a habit of exercising.

Kiwifruit is a type of fruit.

It is consumed in daily meals as a food containing nutrients such as vitamins.

Several studies have been conducted so far on how the fruit kiwifruit relates to our sleep. To date, 4 studies have been reported, and among them are some that used methods considered to be highly reliable.

Summarizing these surveys, it has been suggested that kiwifruit intake may be related to sleep quality. Specifically, the theme of the research is exactly what form this effect on sleep takes.

Looking at the content of the research, 3 of the studies used the method of a randomized controlled trial (a highly reliable research method that randomly divides participants to confirm an effect). In other words, surveys have been conducted following a procedure to check whether the result might simply be due to chance. Overall, suggestions related to sleep have been obtained from multiple studies in which 48 people participated.

What specific changes in condition can be expected from eating kiwifruit? Several studies have examined specific indicators related to sleep quality.

One is research related to falling asleep and nighttime behavior. In a small-scale study with 24 adults with sleep concerns participating (a survey that requires caution regarding the generalizability of results because the number of participants is limited), changes were observed when participants ate 2 kiwifruits each day, 1 hour before bedtime, for 4 weeks. As a result, there are reports that the time from getting into bed to actually falling asleep, and the number of times participants woke up during the night, decreased. In other words, this suggests ease of falling asleep and fewer awakenings during the night.

Research has also been conducted on the relationship with mood. In a survey targeting 24 healthy young men, what happened when fresh kiwifruit or dried green kiwifruit was eaten together with dinner was examined. Here, it has been shown that not only sleep quality but also mood at the time may be positively affected. As one mechanism for this, it has also been proposed that a change in serotonin metabolism (the process by which serotonin, a substance that works in the brain, is broken down or altered in the body) may be involved.

Aspects in which the effect of kiwifruit intake differs depending on the circumstances of the person concerned are beginning to emerge.

For example, in research targeting elite athletes, the results of consuming 2 kiwifruits per day for 4 weeks were examined. This survey suggests a positive effect not only on sleep but also on recovery (returning a body that has become tired from exercise or similar back to its original healthy state).

In addition, from a nutritional perspective, research is also progressing on the relationship between various dietary content and sleep. Besides kiwifruit, the interaction between diet and sleep — such as a dinner high in carbohydrates or specific nutrients — is a widely examined field. In this way, kiwifruit is attracting attention not only as a single food item but also as a target for approaching sleep as part of daily nutritional intake.

Looking at the research data, several points that should be kept in mind also become apparent.

Among the reports on kiwifruit, some are based on observational studies (a method of carefully observing a phenomenon over a set period to explore tendencies). Not all of the research has been proven through rigorous comparative trials. In addition, the number of people who participated in the research was on the scale of 24 or 48, and there is an aspect in which this is not yet sufficient to judge whether it directly applies to the population as a whole.

Therefore, it cannot be stated definitively that eating kiwifruit will always produce the same kind of change in everyone. Depending on an individual's constitution and lifestyle, the expected result may not be obtained, and there will surely be people for whom it does not suit.

The research presents 24 adults with sleep disorders (2 men, 22 women), 24 healthy young men with both good and poor sleep quality, and elite athletes as subjects.

The subjects include adults with sleep concerns, healthy young men, and elite athletes. This serves as material for checking whether your own circumstances are included among the research subjects.

The number of studies is limited to 4.

Of these, 3 are randomized controlled trials (RCTs), while 1 uses another study design.

Caution is also needed regarding the fact that the attributes of the subjects vary widely, including adults with sleep disorders, healthy young men, and elite athletes.

Several studies have reported that kiwifruit may be related to sleep quality and mood. The evidence score is 65, which can be said to be a result of moderate reliability. However, the number of participants in the research is limited, and the same result does not occur in everyone, so it is important to regard this as merely one research report. Please also make use of the self-check assessment to learn about your own sleep condition.