Insomnia is the most common sleep disorder. Although treatments such as cognitive-behavioral therapy have been shown to be effective, there are limitations in terms of effects, accessibility, and cost. It is thus of interest to supplement treatment with more accessible means to increase treatment effects. Little research exists concerning the effects of nutrition on sleep. Kiwi fruit contains rich levels of nutrients, such as antioxidants, flavonoids, carotenoids, anthocyanins, folate, and melatonin, all of which could possibly facilitate sleep. Thus, the purpose of this study was to investigate whether kiwi had beneficial effects on sleep compared to a control fruit chosen on the basis of differences in relevant nutritional content. In this randomized controlled trial, 74 students suffering from chronic insomnia symptoms were instructed to ingest either 130 g of kiwi or pear, the latter comprising the control condition, 1 h before bedtime every day for 4 weeks following 1 week of baseline assessment. Outcome measures consisted of sleep diaries and actigraphy. In addition, we administered the Bergen Insomnia Scale and Pittsburgh Sleep Questionnaire Index. Results showed that on a total of two out of 12 outcome variables (sleep quality and daytime functioning as reported using sleep diary), there was a statistically significant group × time interaction effect favoring the kiwi condition compared to pear. Although there were no such effects using objective measures, the results suggest that kiwi may possess some sleep improving properties. Strengths and limitations of the study are discussed.
Insomnia Nutrition Sleep Kiwi Fruit Randomized controlled trial
This is a preview of subscription content, log in to check access.
Compliance with ethical standards
Regional Committee for Medical and Health Research Ethics in Western Norway No. 2014/2174/REK West.
Conflict of interest
None of the authors declares any conflicts of interest.
University of Bergen and the Regional Research Council of Norway provided funding.
American Psychiatric Association. Diagnostic and statistical manual of mental disorders, 5th ed. 2013. American Psychiatric Association, Washington, DC.Google Scholar
Ohayon MM. Epidemiology of insomnia: what we know and what we still need to learn. Sleep Med Rev. 2002;6(2):97–111.CrossRefPubMedGoogle Scholar
Pallesen S, et al. Prevalence of insomnia in the adult Norwegian population. Sleep. 2001;24(7):771–9.PubMedGoogle Scholar
Pallesen S, et al. A 10-year trend of insomnia prevalence in the adult Norwegian population. Sleep Med. 2014;15:173–9.CrossRefPubMedGoogle Scholar
Sivertsen B, et al. Does insomnia predict sick leave? The Hordaland Health Study. J Psychosom Res. 2009;66:67–74.CrossRefPubMedGoogle Scholar
Sivertsen B, et al. The long-term effect of insomnia on work disability—the HUNT-2 historical cohort study. Am J Epidemiol. 2006;163:1018–24.CrossRefPubMedGoogle Scholar
Baglioni C, et al. Insomnia as a predictor of depression: a meta-analytic evaluation of longitudinal epidemiological studies. J Affect Disord. 2011;135:10–9.CrossRefPubMedGoogle Scholar
Sivertsen B, et al., Midlife insomnia and subsequent mortality: the Hordaland health study. BMC Public Health, 2014. 14:article no. 720.CrossRefPubMedGoogle Scholar
Rybarczyk B, et al. Cognitive behavioral therapy for insomnia in older adults: background, evidence, and overview of treatment protocol. Clin Gerontol. 2013;36:70–93.CrossRefGoogle Scholar
Qaseem A, et al. Management of chronic insomnia disorder in adults: a clinical practice guideline from the American College of Physicians Management of Chronic Insomnia Disorder in Adults. Ann Intern Med. 2016;165:125–33. Google Scholar
Ebben M, Lequerica A, Spielman A. Effects of pyridoxine on dreaming: a preliminary study. Percept Mot Skills. 2002;94:135–40.CrossRefPubMedGoogle Scholar
Ohta T, et al. Treatment of persistent sleep-wake shcedule disorders in adolescents with methylcobalamin (vitamin-B12). Sleep. 1991;14:414–8.PubMedGoogle Scholar
Gominak SC, Stumpf WE. The world epidemic of sleep disorders is linked to vitamin D deficiency. Med Hypotheses. 2012;79(2):132–5.CrossRefPubMedGoogle Scholar
Huang W, et al. Improvement of pain, sleep, and quality of life in chronic pain patients with vitamin D supplementation. Clin J Pain. 2013;29(4):341–7.CrossRefPubMedGoogle Scholar
Kordas K, et al. The effects of iron and/or zinc supplementation on maternal reports of sleep in infants from Nepal and Zanzibar. J Dev Behav Pediatr. 2009;30:131–9.CrossRefPubMedPubMedCentralGoogle Scholar
Held K, et al. Oral Mg(2+) supplementation reverses age-related neuroendocrine and sleep EEG changes in humans. Pharmacopsychiatry. 2002;35:135–43.CrossRefPubMedGoogle Scholar
Spring B, et al. Effects of protein and carbohydrate meals on mood and performance—interactions with sex and age. J Psychiatr Res. 1983;17:155–67.CrossRefGoogle Scholar
Lin HH, et al. Effect of kiwifruit consumption on sleep quality in adults with sleep problems. Asia Pac J Clin Nutr. 2011;20(2):169–74.PubMedGoogle Scholar
Tsaluchidu S, et al. Fatty acids and oxidative stress in psychiatric disorders. BMC Psychiatry. 2008;8(1):1–3.CrossRefGoogle Scholar
Indrawati et al. Comparative study on pressure and temperature stability of 5-methyltetrahydrofolic acid in model systems and in food products. J Agric Food Chem. 2004;52(3):485–92.CrossRefPubMedGoogle Scholar
Kelly GS, Folates. supplemental forms and therapeutic applications. Altern Med Rev. 1998;3(3):208–20.PubMedGoogle Scholar
Hattori A, et al. Identification of melatonin in plants and its effects on plasma melatonin levels and binding to melatonin receptors in vertebrates. Biochem Mol Biol Int. 1995;35(3):627–34.PubMedGoogle Scholar
Bonnefont-Rousselot D, Collin F, Melatonin. Action as antioxidant and potential applications in human disease and aging. Toxicology. 2010;278(1):55–67.CrossRefPubMedGoogle Scholar
Pallesen S, et al. A new scale for measuring insomnia: the Bergen Insomnia Scale. Percept Mot Skills. 2008;107(3):691–706.CrossRefPubMedGoogle Scholar
Faul F, et al. G*Power 3: a flexible statistical power analysis program for the social, behavioral, and biomedical sciences. Behav Res Methods. 2007;39(2):175–91.CrossRefPubMedGoogle Scholar
Huang X, Mazza G. Simultaneous analysis of serotonin, melatonin, piceid and resveratrol in fruits using liquid chromatography tandem mass spectrometry. J Chromatogr A. 2011;1218(25):3890–9.CrossRefPubMedGoogle Scholar
Szeto YT, Tomlinson B, Benzie IF. Total antioxidant and ascorbic acid content of fresh fruits and vegetables: implications for dietary planning and food preservation. Br J Nutr. 2002;87(1):55–9.CrossRefPubMedGoogle Scholar
Voderholzer U, et al. Are there gender differences in objective and subjective sleep measures? A study of insomniacs and healthy controls. Depress Anxiety. 2003;17(3):162–72.CrossRefPubMedGoogle Scholar
Lund HG, et al. The discrepancy between subjective and objective measures of sleep in older adults receiving CBT for comorbid insomnia. J Clin Psychol. 2013;69(10):1108–20.CrossRefPubMedGoogle Scholar
Carskadon MA, Dement WC. Normal human sleep: an overview. Principles Pract Sleep Med. 2005;4:13–23.CrossRefGoogle Scholar