Does kiwi fruit consumption help you sleep better?

Effect of kiwi fruit consumption on sleep quality in adults with sleep problems

Numerous studies have shown that kiwi contains many medicinally useful compounds, including antioxidantsAntioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. In cells, antioxidants such as glutathione, mycothiol or bacillithiol, and enzyme systems like superoxide dismutase, can prevent damage from oxidative stress. and serotoninSerotonin is a monoamine neurotransmitter. Its biological function is complex and multifaceted, modulating mood, cognition, reward, learning, memory, and numerous physiological processes. Approximately 90% of the serotonin that the body produces is in the intestinal tract, which may be beneficial in the treatment of sleep disorders. The aim of this study was to evaluate the effects of kiwi fruit on sleep patterns, including sleep onset, duration and quality. In this study, we applied a free-living, self-controlled diet design. Twenty-four subjects (2 men, 22 women) aged 20 to 55 years consumed 2 kiwifruit one hour before bed each night for 4 weeks.

The Chinese version of the Pittsburgh Sleep Quality IndexThe Pittsburgh Sleep Quality Index (PSQI) is a self-report questionnaire that assesses sleep quality over a 1-month time interval. The measure consists of 19 individual items, creating 7 components that produce one global score, and takes 5–10 minutes to complete. Is intended to be a standardized sleep questionnaire for clinicians and researchers. (CPSQI), a 3-day sleep diary, and the ActigraphActigraphy is a non-invasive method of monitoring human rest/activity cycles. A small actigraph unit, also called an actimetry sensor, is worn for a week or more to measure gross motor activity. The unit is usually in a wristwatch-like package worn on the wrist. sleep/activity clock were used to assess subjective and objective parameters of sleep quality, including time to sleep, time sleep onset, wake time after sleep onset, wake time, total sleep time, and self-reported sleep quality and sleep onset latency, wake time after sleep onset, total sleep time, and sleep efficiency before and after the intervention.

After 4 weeks of kiwi consumption, CPSQI subjective score, wake time after sleep onset, and sleep latency decreased significantly (42.4%, 28.9%, and 35.4%, respectively). Total sleep time and sleep efficiency increased significantly (13.4% and 5.41%, respectively). Kiwifruit consumption may improve sleep onset, duration, and efficiency in adults with self-reported sleep disorders. Further investigation of the sleep-inducing properties of kiwifruit may be warranted.


Difficulty falling asleep or staying asleep, or sleep disturbances associated with impaired daytime functioning, affects up to a third of adults.

Chronic insomnia can lead to an increased risk of depression and the chronic use of hypnotic drugs, it is usually treated with stimulus control therapy, relaxation training and cognitive-behavioral therapy, the judicious use of hypnotic agents, or with non- pharmacological.

Cognitive-behavioral therapy is, however, often difficult and time-consuming to learn, and response to treatment varies widely.

Almost all benzodiazepinesBenzodiazepines, sometimes called “benzos”, are a class of depressant drugs whose core chemical structure is the fusion of a benzene ring and a diazepine ring. They are prescribed to treat conditions such as anxiety, insomnia, and seizures. and nonbenzodiazepines that are effective for the short-term management of sleep disorders produce adverse effects such as daytime sedation, cognitive impairment, dependence, and rebound insomnia.

Other non-pharmacological remedies, including antihistaminesAntihistamines are drugs which treat allergic rhinitis, common cold, influenza, and other allergies. Typically, people take antihistamines as an inexpensive, generic drug that can be bought without a prescription and provides relief from nasal congestion, sneezing, or hives caused by pollen, dust mites, or animal allergy with few side effects. Antihistamines are usually for short-term treatment. with sedative effects and alcohol, are ineffective for long-term treatment. A few days after using antihistamines, patients may develop tolerance to sedation, and adverse effects usually occur within a few days.

With alcohol, there is a risk of addiction and exacerbation of other conditions, such as gastroesophageal reflux, sleep apnea, and increased urinary frequency.

Consequently, natural treatments that can improve both sleep onset and help patients improve sleep quality while ameliorating long-term next-day symptoms are highly desirable.

Kiwifruit (Actinidiaceae) is native to East Asia

Some over-the-counter and herbal products such as kava kava and St. John’s wort are touted as sleep enhancers, but they have not been rigorously studied and there is little evidence that they are effective. Herbal products such as Piscidia piscipulaPiscidia piscipula, commonly named Florida fishpoison tree, Jamaican dogwood, or fishfuddle, is a medium-sized, deciduous, tropical tree native to the Greater Antilles, extreme southern Florida and the Bahamas, and the coastal region from Panama northward to the vicinity of Ocampo, Tamaulipas, Mexico. and kava kavaKava (Piper methysticum) is a crop of the Pacific Islands. The name kava is from Tongan and Marquesan, meaning ‘bitter’. Kava is consumed for its sedating effects throughout the Pacific Ocean cultures of Polynesia, including Hawaii, Vanuatu, Melanesia, some parts of Micronesia, such as Pohnpei and Kosrae, and the Philippines may also pose potential risks.


KiwifruitKiwifruit or Chinese gooseberry is the edible berry of several species of woody vines in the genus Actinidia. The most common cultivar group of kiwifruit (Actinidia deliciosa) is oval, about the size of a large hen’s egg: 5–8 cm in length and 4.5–5.5 cm in diameter. It has a thin, fuzzy, fibrous, tart but edible light brown skin and light green or golden flesh with rows of tiny, black, edible seeds. (Actinidiaceae) is native to East Asia and its use for the treatment of cancer-like diseases, especially of the digestive tract, dates back to 700 BC.

Numerous studies have shown that kiwi fruit contains many medicinally useful compounds such as vitaminsA vitamin is an organic molecule or a set of molecules closely related chemically, that is an essential micronutrient that an organism needs in small quantities for the proper functioning of its metabolism. Essential nutrients cannot be synthesized in the organism, either at all or not in sufficient quantities, and therefore must be obtained through the diet. Vitamin C can be synthesized by some species but not by others., carotenoidsCarotenoids, are yellow, orange, and red organic pigments that are produced by plants and algae, as well as several bacteria, and fungi. Carotenoids give the characteristic color to pumpkins, carrots, parsnips, corn, tomatoes, canaries, flamingos, salmon, lobster, shrimp, and daffodils. Carotenoids can be produced from fats and other basic organic metabolic building blocks by all these organisms. In the human diet, absorption of carotenoids is improved when consumed with fat in a meal. and mineralsA mineral is a chemical element required as an essential nutrient by organisms to perform functions necessary for life. However, the four major structural elements in the human body by weight (oxygen, hydrogen, carbon, and nitrogen), are usually not included in lists of major nutrient minerals. These four elements compose about 96% of the weight of the human body, and major minerals (macrominerals) and minor minerals (also called trace elements) compose the remainder..

It is well known that patients with sleep disorders and various neuropsychiatric conditions show increased levels of oxidative stress. Kiwi is rich in antioxidants, vitamins C and E, flavonoidsFlavonoids (or bioflavonoids; from the Latin word flavus, meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans., anthocyaninsAnthocyanins, also called anthocyans, are water-soluble vacuolar pigments that, depending on their pH, may appear red, purple, blue, or black. Food plants rich in anthocyanins include the blueberry, raspberry, black rice, and black soybean, among many others that are red, blue, purple, or black. Some of the colors of autumn leaves are derived from anthocyanins. and carotenoids and contains about twice as much serotonin as tomato.

Serotonin is an end product of L-tryptophan metabolism, which is linked to rapid eye movement (REMRapid eye movement sleep (REM sleep or REMS) is a unique phase of sleep in mammals and birds, characterized by random rapid movement of the eyes, accompanied by low muscle tone throughout the body, and the propensity of the sleeper to dream vividly.
The REM phase is also known as paradoxical sleep (PS) and sometimes desynchronized sleep or dreamy sleep, because of physiological similarities to waking states including rapid, low-voltage desynchronized brain waves.
) sleep, and its low levels can cause insomnia. In addition, kiwi is rich in folic acidFolate, also known as vitamin B9 and folacin, is one of the B vitamins. Folate is required for the body to make DNA and RNA and metabolise amino acids necessary for cell division. As humans cannot make folate, it is required in the diet, making it an essential nutrient., and insomnia is one of the neuropsychiatric diseases that are secondary to folate deficiency.

Therefore, it is possible that kiwifruit consumption is beneficial in improving sleep quality in those with sleep disorders.

This study was designed to evaluate the effects of kiwi consumption on various subjective and objective measures of sleep quality, as measured by Actigraph and a sleep diary, in individuals complaining of sleep disturbances.


Twenty-nine subjects, 5 men and 24 women, aged 20 to 55 years, participated in this study. Of the 29 eligible subjects, 24 ultimately completed the study, as data were incomplete for 3 subjects and 2 subjects left the study early.

Table 1 shows the age and gender-structured physical characteristics of the last 24 subjects with self-reported sleep problems. There were no significant differences in age, body weight and BMIBody mass index (BMI) is a value derived from the mass (weight) and height of a person. The BMI is defined as the body mass divided by the square of the body height, and is expressed in units of kg/m2, resulting from mass in kilograms and height in metres. between male and female subjects (p>0.05). However, males were taller than females (1.70±0.04 m vs. 1.59±0.05 m, p=0.036). A total of 13 participants had health problems associated with sleep disorders. Of these, 7 participants had sleep disturbances due to stress. Two female participants experienced sleep disturbances due to dysmenorrhea.

The remaining four participants experienced sleep disturbances due to stomach ache or flu.

Differences in measurements before and after the intervention are shown in Table 2. There were significant differences in total sleep time (TST) and sleep efficiency measured by the Actigraph Sleep/Activity Logger before and after the intervention (p<0.05). Statistically significant increases of 16.9% and 2.4% were found for TST and sleep efficiency, respectively. When measured by sleep diary, CPSQI, WASO and SOL scores decreased significantly by 42.4% (p<0.001), 28.9% (p=0.002) and 35.4% (p <0.001). In contrast, TST and sleep efficiency increased significantly by 13.4% (p=0.007) and 5.41% (p=0.001), respectively.

Table 3 shows that there were no significant differences in WASO, SOL, TST, or sleep efficiency between objective (Actigraph) and subjective (personal sleep diary) measurements.

Table 1

Demographics and clinical conditions of participants stratified by gender (n=24)

Total (n=24) Male (n=2) Female (n=22) p-value
Age (years) 34.4±12.9 27.0±5.66 35.1±13.3 0.637
Height (m) 1.60±0.06 1.70±0.04 1.59±0.05 0.036*
Body weight (kg) 54.1±8.03 56.5±3.54 53.9±8.33 0.270
BMI (kg/m2) 21.2±2.69 19.5±0.25 21.2±2.77 0.531
Health problems associated with sleep disorder (number of patients)
Stress 7 0 7 1.000
Dysmenorrhea 2 0 2 1.000
Flu 2 0 2 1.000
Stomach ache 2 1 1 0.163


*Significant difference using Mann-Whitney U test , p-value

Table 2

Difference in measurements after the 4-week intervention (n=24)





Subjective measurements**

Waking time after sleep onset (min)




Sleep onset latency (min)




Total sleep time (min)




Sleep efficiency (%)




CPSQI score




Objective measurements***

Waking time after sleep onset (min)




Sleep onset latency (min)




Total sleep time (min)




Sleep efficiency (%)




*Significant differences using Wilcoxon signed rank test, p <0.05

Values expressed as mean ± standard error

** By sleep diary

*** By Actigraph watch

Table 3

Percent of change from baseline, after 4-week intervention, between subjective and objective measurements (n=24)


Subjective measurement**

Objective measurement***


Waking time after sleep onset (%)




Sleep onset latency (%)




Total sleep time (%)




Sleep efficiency (%)





*Significant differences, p<0.05. P-values are based on linear mixed model

Values expressed as mean ± standard error

**By sleep diary

*** By Actigraph watch 


The results of this study showed that sleep quality was significantly improved in adult subjects after a 4-week regimen of kiwi consumption. Even with minimal discrepancies between subjective and objective measurements, the results demonstrated that after 4 weeks kiwi consumption improved sleep quality in terms of increasing total sleep duration and sleep efficiency.

Regarding the inconsistencies between objective and subjective measurements, we added the MiniMotionlogger Actigraph wristwatch to the objective measurements as an additional and more reliable measure of sleep quality than the subjective measurements, which we suspected might not provide sufficiently reliable evidence.

Numerous physiological and pathological processes, including sleep disturbances and emotional or physiological stress, increase the body’s concentration of oxidizing substances known as reactive oxygen species (ROSROS are byproducts of the normal metabolism of oxygen. ROS have roles in cell signaling and homeostasis. ROS are intrinsic to cellular functioning, and are present at low and stationary levels in normal cells. However, ROS can cause irreversible damage to DNA as they oxidize and modify some cellular components and prevent them from performing their original functions. ), more commonly known as free radicals. These substances are derived from overexpression of inflammatory cytokines and mediators and ultimately lead to depletion of endogenous antioxidants and subsequent compromise of homeostatic mechanisms involving neurotransmitters.


It has previously been reported that there are 85 mg of vitamin C and 1.6 mg of vitamin E in 100 grams of fresh edible Hayward kiwifruit, representing 94% and 11% of the recommended daily allowance (RDI), respectively. Szeto et al. reported that kiwi fruit (unspecified variety) contained the highest proportion of ascorbic acid compared to a large group of fruits including strawberry, lemon, plum, orange, grapefruit, apple, tangerine, mango, grape, banana, pear, pineapple, and Chinese pears.

Flavonoids, anthocyanins and carotenoids have been found in kiwifruit, which may also contribute to its antioxidant capacity. Therefore, the abundance of antioxidants in kiwi could be a possible mechanism explaining its effects on improving sleep quality. The amount, timing, and duration of kiwi consumption required to study its potential effects on sleep patterns were determined based on protocols and results of previous studies. In two previous studies, subjects ate 2 kiwifruit (100g each) at a time, and the researchers noted that this was the amount most participants would accept.


In a study of the effects of food on glucose tolerance throughout the day, Nilsson et al. determined that the time required for blood sugar to peak after a meal is approximately 60 minutes; and in previous in vivo experiments on kiwi digestion by four nonatopic healthy volunteers, examination of gastric contents one hour after kiwi ingestion was adopted, as digestion of pectin-rich foods was complete at that time.

These protocols encouraged our subjects to consume kiwi an hour before bedtime so that the fruit is fully digested and absorbed by the digestive system, allowing the effects to be monitored. In most previous studies and clinical trials on kiwi consumption, the protocols were designed for 3-4 weeks of kiwi consumption. Duttaroy and Jorgenson asked study subjects to consume 2 and 3 kiwis per day for successive 28-day periods separated by at least 2-week washout periods to examine platelet aggregation and plasma lipids in healthy adults.

REM sleep activity

In a study by Chan et al., both patients and controls were given 2 kiwis (one in the morning after breakfast and one in the evening after dinner) for four weeks, during which time examiners tracked the effects of eating fiber on functional constipation. Even though the study objectives varied, the above protocols influenced the adoption in our study protocol of 2 kiwis consumed in the evening one hour before bed for 4 weeks of the study period.

Serotonin is an end product of L-tryptophan metabolism, which is linked to REM sleep, and its low levels can cause insomnia. Patients with primary insomnia showed a significant decrease in serum tryptophan concentrations and a significant increase in indices of phasic REM sleep activity (REM density) compared to baseline values.

The results of the radio-enzymatic analyzes of serotonin revealed a high content of serotonin in kiwi fruit (pulp-edge: 6.8 µg/g; pulp-center: 3.0, per 30 mg of kiwi), which could be another possible mechanism contributing to the sleep-enhancing effects.

Folate deficiency has been suggested to lead to insomnia and restless legs syndrome. Neuropsychiatric diseases secondary to folate deficiency may include dementia, schizophrenia-like syndromes, and insomnia. Although folate is abundant in the diet, it is easily destroyed by cooking or processing. Kiwi has an advantage in that it is consumed raw and contains 0.23±0.04 μg/g of total folate, which is almost 80% higher than that in carrot juice and 15% higher than that in apple juice. oranges. It is estimated that a single kiwi contains about one tenth of the average daily requirement of folic acid. Thus, it is possible that the folate intake from raw kiwi fruit is also a beneficial mechanism for improving sleep quality.


The results of this study may lead to prospective studies examining the underlying sleep-promoting mechanisms found in “kiwifruit therapy.” However, this study has limitations and caution should be used in interpolating these conclusions because the study sample, in addition to being small, was recruited based on self-reported sleep disturbances rather than actual clinical diagnoses ( that is, it was unclear whether the sleep disturbances were comorbid or primary). We asked whether participants had experienced sleep disturbances due to health problems in the past month. A total of 13 participants had health problems associated with sleep disturbances, which included stress, dysmenorrhea, stomach aches or the flu.

However, those health problems did not occur consistently. Additionally, we were unable to determine the degree of subject expectancy effect arising from the lack of crossover design or placebo (control). A strength of the study was the use of objective (use of the Actigraph sleep/activity watch) and subjective (CPSQI scores and sleep diaries) means to assess specific parameters of sleep quality.

In summary, consuming 2 kiwis per night 1 hour before bedtime for 4 weeks improved sleep onset, duration, and efficiency in adults with self-reported sleep disturbances. The results of this study suggest that further research into the sleep-inducing mechanisms of kiwifruit may be warranted.


This study was supported by Zespri International Limited, Taiwan. The authors would also like to thank all study participants.

Hsiao-Han Lin MS – School of Nutrition and Health Sciences, Taipei Medical University, Taipei, Taiwan

Pei-Shan Tsai PhD – College of Nursing, Taipei Medical University, Taipei, Taiwan

Su-Chen Fang MS – College of Nursing, Taipei Medical University, Taipei, Taiwan

Jen-Fang Liu PhD – School of Nutrition and Health Sciences, Taipei Medical University, Taipei, Taiwan


APJCN – Asia Pacific Journal of Clinical Nutrition