Sleep and Biological Rhythms

, Volume 15, Issue 2, pp 159–166 | Cite as

The effects of kiwi fruit consumption in students with chronic insomnia symptoms: a randomized controlled trial

  • Øystein Ottesen NødtvedtEmail author
  • Anita Lill Hansen
  • Bjørn Bjorvatn
  • Ståle Pallesen
Original Article


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 


Compliance with ethical standards

Ethical approval

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.


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Copyright information

© Japanese Society of Sleep Research 2017

Authors and Affiliations

  1. 1.Department of Psychosocial ScienceUniversity of BergenBergenNorway
  2. 2.Department of Clinical PsychologyUniversity of BergenBergenNorway
  3. 3.Centre for Research and Education in Forensic PsychiatryHaukeland University HospitalBergenNorway
  4. 4.Norwegian Competence Center for Sleep DisordersHaukeland University HospitalBergenNorway
  5. 5.Department of Global Public Health and Primary CareUniversity of BergenBergenNorway

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