The Effects Of Kiwifruit Consumption On Sleep Quality, Fatigue And BMI In Saudi Students With Poor Sleep Quality: A 6-Week Pilot Randomized Controlled Trial
Phase: NA
Conditions: Sleep Disturbance, Fatigue, Body Weight
Sponsor: Umm Al-Qura University

Date:2021/11/30 
Brief title: The Effects Of Kiwifruit Consumption On Sleep Quality, Fatigue And 
BMI Of Saudi Adults  
Official title: The Effects Of Kiwifruit Consumption On Sleep Quality, Fatigue 
And BMI In Saudi Students With Poor Sleep Quality: A 6-Week Pilot Randomized 
Controlled Trial 
Essra Noorwali a*, Nafeesah Noorwali a,Abeer Aljaadia, Shahad Shuaib a, Sarah Alrehili a, Hadeer 
Abidah a, Shatha Allehaibi a 
aClinical Nutrition Department, Faculty of Applied Medical Sciences, Umm Al-Qura University, 
Makkah, 21955, Saudi Arabia  
*Corresponding author: Essra A. Noorwali. Email: eanoorwali@uqu.edu.sa  
Address: Department of Clinical Nutrition, Faculty of Applied Medical Sciences, Umm Al-Qura 
University, Makkah, 21955, Saudi Arabia 
ORCID ID: https://orcid.org/0000-0002-8312-402X   
Funding: None 
Declaration of Interest: None 
 
 
 
 
 
 

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Brief summary 
 
Hypothesis: Kiwifruit contains antioxidants and serotonin which may be beneficial in the treatment 
of sleep disruption. Aim: to assess the effects of daily intake of kiwifruit on sleep quality, fatigue, 
and BMI among Saudi adults with poor sleep quality. Methods: Twenty-six female participants 
(14 cases, and 12 controls) were included. All participants were aged ≥18 years and were Saudi 
and had poor sleep quality.  Pregnant, lactating and participants with any chronic diseases such as 
cardiovascular or neurological diseases, and history of using herbal or medications for inducing 
sleep for the last two months were excluded.  Participants in the case group consumed 2 kiwifruits 
1 hour before bedtime nightly for 6 weeks and the control group did not consume kiwifruit. The 
Pittsburgh Sleep Quality Index (PSQI) questionnaire was used to assess sleep quality before and 
after kiwi consumption (score ≥ 5 indicates poor sleep quality), Fatigue Severity Scale (FSS) was 
used to assess fatigue and anthropometrics were measured based on the WHO guidelines. After 6 
weeks, sleep quality, fatigue and BMI were compared between cases and controls. Kiwifruit 
consumption may improve sleep quality in adults with self-reported poor sleep quality. Further 
investigation of the sleep promoting properties of kiwifruit is required. 
 
 
 
 

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Introduction  
People spend almost one third of their lives in sleep and it is one of the main contributors to our 
life and wellbeing [1]. Sleep quality has several components including sleep duration, timing, 
efficiency (time in bed spent asleep) and latency (the amount of time it takes to fall asleep).  Sleep 
disruption may be defined as any change in the components of sleep quality [2]. A cross-country 
comparative analysis reported the economic cost of insufficient sleep from 62,000 people in UK, 
US, Canada, Germany, and Japan. Insufficient sleep costs $411 billion annually for the US, $138 
billion for Japan, £40 billion for UK, $60 billion for Germany, and $21 billion for Canada [3]. No 
study has measured the economic cost of sleep disruption in Saudi Arabia. This may be due to the 
fact that sleep medicine is relatively a new specialty in the medical community [4].  
 
The National Sleep Foundation recommends different sleep durations for individuals according to 
age. Adults aged between 18–64 years are recommended to sleep 7–9 h/day [5]. In Saudi Arabia, 
33.8% of adults sleep less than 7 hours, and this was shown in women more than men [6]. In meta-
analyses, short sleep duration has been associated with an increased risk of obesity [7] [8]. Sleep 
disruption has been shown to increase the risk of cancer [9][10], type 2 diabetes mellitus [7], 
cardiovascular disease and coronary heart disease [11]. Furthermore, sleep disruption has been 
associated with an increased risk of mortality [7,12,13]. Collectively, sleep disruption has 
detrimental economic and health consequences and identifying the factors that may improve it is 
a public health priority. Thus, using interventions to improve sleep quality may help reduce disease 
risk and occurrence. 
 
Nutritional research studied the effects of micro and macronutrients and whole foods on sleep 
measures. Micronutrients studied in relation to sleep included tryptophan, zinc, B-vitamins and 
polyphenols [14]. A recent systematic review explored the effects of macronutrient manipulation 
on sleep outcomes. Manipulating carbohydrate intake appeared to alter sleep outcomes in healthy 
individuals [15]. Several food items were studied in relation to sleep outcomes including fish [16] 
tart cherry juice and products[17–20] and kiwi fruit [21,22]. Despite these studies, nutritional 
advice that can be recommended for sleep hygiene is inconclusive due to limited interventional 
studies.  
 

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Recently, kiwifruit has gained interest in regards to sleep outcomes [23]. This may be due to the 
potential mechanisms of kiwifruit on sleep. Kiwifruit contain melatonin [24] which is important 
for regulating the circadian rhythms and sleep cycles [25]. Another potential mechanism is the 
high content of polyphenols, antioxidants, flavonoids, carotenoids, and anthocyanins that may 
decrease oxidative stress in people with sleep disorders or poor sleep quality. Furthermore, 
polyphenols may influence sleep through their effects on circadian rhythms, clock gene 
expression, and peripheral clocks [2]. Kiwifruits contain a protein named actinidin which is 
involved in precursors of neurochemicals required for sleep-wake regulation. In addition, kiwifruit 
is rich in folate and vitamin c which are essential in the metabolism of amino acids into 
neurochemicals [23]. Regardless of the potential mechanisms of kiwifruit on sleep, only two 
interventional studies were conducted [21,22] to explore this relationship. However, the study 
conducted by Lin et al. did not include a control group [21] and the intervention period in Nødtvedt 
et al. study was only 4 weeks [22].  
Therefore, we designed the study with the purpose of replicating the study with a control group 
and a longer intervention period to investigate whether kiwi has beneficial properties on sleep. We 
conducted a randomized, controlled trial addressing whether intake of kiwifruit would improve 
sleep parameters in a Saudi student population with poor sleep quality.  
 
This study aims to 1) compare between sleep, fatigue and BMI in cases and controls at the start 
of the study and after 6 weeks in Saudi adults 2) Study the effects of kiwifruit consumption on 
sleep quality, fatigue, and BMI in Saudi adults.  
 
Study Hypothesis: Kiwifruit intake may improve sleep quality, fatigue and decrease BMI 
 
 
 
 
 
 
 
 

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Materials and methods  
Study design: a pilot randomized controlled trial (Figure 1.) 
 
Figure 1. Methodology and study design  
 
Legend: FSS: Fatigue Severity Scale, PSQI: The Pittsburgh Sleep Quality Index, SR: Saudi Riyal, 
UQU: Umm Al-Qura University  
 
Participants: The study included university students aged ≥ 18 years with poor sleep quality from 
Umm Al-Qura University, Makkah, Saudi Arabia. Ethical approval was obtained from the 
Biomedical Research Ethics Committee at Umm Al-Qura University. No. HAPO-02-K-012. This 
study was carried out in accordance with the principles of the Helsinki Declaration. Participants 
were recruited through email and several social media platforms including WhatsApp™ and 
Twitter™ by a flyer between January-February 2022. Participants were invited to a screening visit 
(30-45 minutes) at Umm Al-Qura University Nutrition clinic to assess eligibility. In the screening 
visit, researchers explained the study aims and provided participants with a consent form and a 
kiwifruit consumption diary if eligible (Figure 1.).  
 
Recruitment status: Completed  
 
Inclusion/exclusion criteria: Eligibility to participate in the study; aged ≥ 18 years, have poor 
sleep quality that was assessed in the screening visit by the PSQI (a score of at least 5) (Kim et al. 
2020; Tsai et al. 2005). Pregnant and lactating women were excluded due to their poor sleep quality 
[26],[27]. In addition, participants with any chronic diseases such as cardiovascular or neurological 

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diseases, and history of using herbal or medications for inducing sleep for the last two months 
were excluded.  
Eligible participants signed a consent form for their agreement to participate and they were 
informed that their participation will be anonymous. After that, they were asked by the researchers 
a group of questions including demographic, fatigue questions, sleep quality and their height and 
weight were measured. Eligible participants were randomized by a lottery-based method to 
randomize the participants into two groups: a case or control group. After 6 weeks, eligible 
participants (cases and controls) attended a second visit.  
 
Questionnaires:  
A questionnaire was created to be filled in by the participants in both visits (Figure 1). The 
questionnaire included a brief introduction and a consent statement “I agree to participate in this 
study. Before finishing the trial, I can freely and without consequences terminate my 
participation”. In addition, it included demographic questions, sleep quality questionnaire (PSQI) 
and the Fatigue Severity Scale (FSS).  
 
Sleep quality  
Sleep quality was  assessed using the validated Pittsburgh Sleep Quality Index (PSQI) [28], which 
is an 18-item questionnaire. Two language versions of the PSQI were used; English [28], and the 
Arabic version that was translated by 10 Arabic bilingual translators was used [29]. The PSQI is a 
subjective measure that assesses seven factors of sleep: sleep quality, sleep latency, sleep duration, 
habitual sleep efficiency, sleep disturbances, use of sleep medication and daytime dysfunction. 
Each dimension scored between 0–3, with a total score ranging from 0–21. Higher scores indicate 
lower sleep quality. A global PSQI score higher than 5 points indicates poor sleep quality [28]. 
Moreover, to analyze variables not considered by the PSQI, we included in the survey questions 
of stability of participants usual sleep/wake patterns and if they differ on weekends and how often 
they had naps. 
 
 
 
 

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The Fatigue Severity Scale (FSS) 
Fatigue was assessed using the Fatigue Severity Scale (FSS) which is a self-administered 
questionnaire with 9 items (questions) investigating the severity of fatigue in different situations 
during the past week. Grading of each item ranges from 1 to 7, where 1 indicates strong 
disagreement and 7 strong agreements, and the final score represents the mean value of the 9 items 
[30]. The researchers independently translated the original version of the questionnaire from 
English to Arabic. Prior to use in this study, the questionnaire was initially administered to 10 
bilingual subjects, who completed both the Arabic version and the English version to determine 
the test–retest reliability. Fatigue was independent of the version. 
 
Study intervention 
Eligible participants were randomly assigned  to either a non-kiwifruit feeding group (controls) or 
consumed two medium-size kiwifruit group [21] (cases) 1 hour before bedtime every night for 6 
weeks (42 days in total). Randomization was performed by giving participants a note identifying 
the condition to which they were randomized; the note was placed in a sealed envelope. Blindness 
was not applicable since cases received kiwifruit and controls did not receive. Total number of 
kiwis consumed should be (14 kiwis (number of kiwis in one week) x 6 (number of weeks) = 84 
kiwis in total.  Participants consuming the kiwifruit were asked to keep a diary to record if they 
consumed them every day. During the 6-week intervention period, participants received their 
kiwifruit every week on the first day of the week (Sunday) that is adequate for a week (14 kiwi 
fruits brand name: Sharbatly Co. Ltd, variety: Hayward, country of origin: Italy). The kiwifruits 
were supplied at optimum ripeness for consumption and were instructed to keep the kiwi in the 
fridge to prevent damage.  
 
Anthropometric measurements  
Participants’ weight and height were measured via (GIMA Pegaso Digital Scale) on both visits to 
calculate their body mass index (BMI). WHO guidelines were used to take physical measurements 
of participants [31]and BMI categorization was based on WHO [32]. 
 
 
 

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Statistical Analysis 
Data analysis was performed using Statistical Package for the Social Sciences, SPSS 23rd version. 
Frequency and percentages were used to display categorical variables. Mean and standard 
deviation were used to present numerical variables. The Shapiro-Wilk test was used to test 
normality. Independent t-test and paired t-test were used to test associations for normally 
distributed variables (age, duration of nap, BMI at both start and end of the study, fatigue score at 
both start and end of the study, PSQI at end of the study). While the Mann-Whitney U test and 
Wilcoxon Signed-Rank test were used for non-normally distributed variables (PSQI at start of the 
study). Pearson’s correlation was also used to test for associations between numerical variables. 
The level of significance was set at 0.05.  
 
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Informed Consent form
 
Consent statement 
 
I hereby confirm that all aspects related to the study have been explained to me including aims and procedures and 
that the study (does/does not) include any experimental therapies and that my participation is voluntary with no 
extra-expenses and there (is/is no) payment offered to me for participation. I have been given a copy of data 
related to the study and a copy from this consent. 
Signature of the participant: 
 
 
Date of consent(To be personally dated by the participant) 
 
Date of the consent(personally dated by the participant’s guardian if applicable) 
Name of the Principal Investigator (or delegate) 
 
 
Signature of the Principal Investigator (or delegate) 
 
Date of the consent (To be personally dated by the Principal Investigator or delegate) 
Name of the witness (if applicable) 
Signature of the witness(if applicable) 
Date of the consent (To be personally dated by the witness(