Sleep disorders ruin the evenings of many adults, to the point of weighing on mood, memory and cardiovascular health. Rather than immediately turning to supplements, several teams have observed the effect of a simple autumn fruit, eaten in the evening, on the quality of rest. A study published in theAsia Pacific Journal of Clinical Nutrition describes surprisingly fast results on falling asleep time.
This fruit is the kiwi. In this study conducted by Taipei Medical University, adults with poor sleep ate 2 kiwis about 1 hour before bedtime, every evening for four weeks. Their average sleep onset latency decreased by about 35%, while total sleep duration and efficiency increased. A more recent study published in 2023 in the journal Nutrients, among elite athletes, found a similar benefit with the same evening ritual.
How many kiwis in the evening, and for how long
Concretely, researchers from the Asia Pacific Journal of Clinical Nutrition asked 24 adults aged 20 to 55, who complained of sleep problems, to eat two kiwis one hour before going to bed, every evening for four weeks. The rest of their diet remained usual, which made it possible to target the effect of this specific snack.
They assessed sleep quality with the Pittsburgh Sleep Quality Index and by actigraphy, which records movements during the night. After four weeks, the overall sleep quality score had decreased by about 42%, time to fall asleep by about 35%, time awake after falling asleep by almost 29%, while total sleep time increased by about 13%. Sleep efficiency, that is to say the part of the night actually spent sleeping, increased by a little more than 5%.
Why evening kiwi could help you sleep better
Kiwi naturally provides serotonin and many antioxidants, two elements cited by the authors as possible avenues to explain these results. Serotonin serves as a precursor to melatonin, the hormone that prepares the brain for sleep. This fruit also has a low glycemic index and contains potassium, calcium, magnesium and fiber, nutrients which contribute to a general state of relaxation.
A team tested this same ritual “2 kiwis one hour before bed” in 2023 on 15 elite athletes in the journal Nutrients. Their average score on the Pittsburgh Sleep Quality Index fell from 6.47 to 4.13, and the proportion of “poor sleepers” fell from about 87% to 33%. Athletes also reported less general and training-related stress.
Precautions before adopting kiwis as a sleep aid
However, these two studies remain small, without a placebo group or random draw, which prevents us from asserting that kiwi is sufficient to treat insomnia. The participants already had disturbed sleep, and the fruit does not replace real sleep hygiene.
People prone to reflux, heartburn or allergic to kiwi should avoid eating it just before bed and talk to their doctor.