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

Introduction People spend almost one third of their lives in sleep and it is one of the main contributors to our life and wellbeing. 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. 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. 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.

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. In Saudi Arabia, 33.8% of adults sleep less than 7 hours, and this was shown in women more than men. In meta-analyses, short sleep duration has been associated with an increased risk of obesity. Sleep disruption has been shown to increase the risk of cancer, type 2 diabetes mellitus, cardiovascular disease and coronary heart disease. Furthermore, sleep disruption has been associated with an increased risk of mortality. 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. A recent systematic review explored the effects of macronutrient manipulation on sleep outcomes. Manipulating carbohydrate intake appeared to alter sleep outcomes in healthy individuals. Several food items were studied in relation to sleep outcomes including fish tart cherry juice and products and kiwi fruit. Despite these studies, nutritional advice that can be recommended for sleep hygiene is inconclusive due to limited interventional studies.

Recently, kiwifruit has gained interest in regards to sleep outcomes. This may be due to the potential mechanisms of kiwifruit on sleep. Kiwifruit contain melatonin which is important for regulating the circadian rhythms and sleep cycles. 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. 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. Regardless of the potential mechanisms of kiwifruit on sleep, only two interventional studies were conducted to explore this relationship. However, one study did not include a control group and the intervention period in another study was only 4 weeks.

Therefore, investigators 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. Investigators conducted a randomized, controlled trial addressing whether intake of kiwifruit would improve sleep parameters in a Saudi student population with poor sleep quality.