A study examining the effects of green kiwifruit on sleep quality and the sleep-wake cycle in males has been awarded $31,800 of funding.

The work builds on previous research, which found that sleep quality improved with the consumption of two New Zealand-grown green kiwifruit every day for four weeks.

The research team will investigate whether the consumption of fresh green kiwifruit flesh will increase the urinary concentration of metabolites central in the regulation of sleep-wake cycles, and whether these effects are enhanced using a freeze-dried form of kiwifruit that includes the skin of the fruit.

Better sleep

“There is some evidence from scientific studies that kiwifruit promotes sleep but how it does that we don’t really know,” says Massey University senior lecturer Dr Sharon Henare.

“We’re interested in identifying the mechanism by which kiwifruit may be acting to improve sleep and whether this involves an increase in the neurochemicals responsible for the regulation of sleep-wake cycles.

“The potential to use a natural product, such as having kiwifruit after dinner, appeals as a simple solution to improve sleep.”

The project also aims to determine the effect of green kiwifruit on self-reported psychological wellbeing.

Sleep promoting foods have been shown to increase the levels of the neurohormone melatonin and its precursor serotonin. Both hormones play central roles in the regulation of sleep-wake cycles.

New Zealand kiwifruit’s nutrient-dense flesh and skin is high in vitamin C, folate and fibre. Kiwifruit also contains six micrograms per gram of serotonin, which is considered high.

Market potential

The funding will be allocated over 12 months by the High-Value Nutrition Ko Ngā Kai Whai Painga National Science Challenge.

“This study strongly aligns with HVN’s mission and strategy to develop high-value foods with validated health benefits to drive economic growth through research excellence,” says HVN challenge director Joanne Todd.

“The anticipated outcomes may reveal the potential for the formulation of unique Aotearoa New Zealand kiwifruit-based products with health messaging related to sleep quality and mood, while also potentially bringing increased economic benefits for kiwifruit growers.”

The study is being conducted by PhD candidate Alex Kanon under the supervision of Dr Sharon Henare and in collaboration with Zespri.