Michael Greger, MD
The number one question in sleep research is why do we sleep? And then comes the question – how many hours of sleep do we need? After literally hundreds of studies, we still don’t know the right answers to these questions. A few years ago, I did a large study of 100000 people showing that too little and too much sleep were associated with increased mortality, and that people who slept about seven hours a night lived longer. After that, a meta-analysis was conducted, which included more than a million people, it showed the same thing.
We still don’t know, however, whether sleep duration is the cause or just a marker of poor health. Maybe too little or too much sleep makes us unhealthy, or maybe we die early because we are unhealthy and that makes us sleep more or less.
Similar work has now been published on the effects of sleep on cognitive function. After taking into account a long list of factors, it turned out that men and women in their 50s and 60s who get seven or eight hours of sleep have better short-term memory compared to those who sleep much more or much less. The same thing happens with immune function, when the usual duration of sleep is reduced or lengthened, the risk of developing pneumonia increases.
It’s easy to avoid sleeping too much – just set an alarm. But what if we’re having trouble getting enough sleep? What if we are one of three adults who experience symptoms of insomnia? There are sleeping pills, such as Valium, we can take them, but they have a number of side effects. Non-pharmacological approaches, such as cognitive behavioral therapy, are often time-consuming and not always effective. But it would be great to have natural therapies that can improve sleep onset and help improve sleep quality, relieving symptoms instantly and permanently.
Kiwi is an excellent remedy for insomnia. Study participants were given two kiwis an hour before bed every night for four weeks. Why kiwi? People with sleep disorders tend to have high levels of oxidative stress, so perhaps antioxidant-rich foods might help? But all fruits and vegetables have antioxidants. Kiwis contain twice as much serotonin as tomatoes, but they cannot cross the blood-brain barrier. Kiwi contains folic acid, a deficiency of which can cause insomnia, but there is much more folic acid in some other plant foods.
The scientists got some really remarkable results: significantly improved the process of falling asleep, the duration and quality of sleep, subjective and objective measurements. Participants began to sleep an average of six hours a night to seven, just by eating a few kiwis.