Whether you struggle with getting to sleep, staying asleep, or feeling properly rested, we all know the groggy feeling that comes with a bad night’s slumber (or two, or three…).
You’re not alone with sleep problems, at least one third of Americans aren’t getting the recommended 7 hours minimum a night. This doesn’t just make us feel groggy and sluggish, it affects every aspect of our health, including our risk of developing type 2 diabetes, heart disease, obesity, and depression, just to name a few 1 2.
If you struggle to get enough sleep, you’ve probably tried most tricks in the book, such as the tips recommended by the American Academy of Sleep Medicine. These include having a good routine, sleeping in a cool, dark, cold environment, and only sleeping when you are tired.
Most of us also know of the food and drink to avoid for a better night's rest: caffeine, alcohol, and large meals.
Low and behold, the role our diet plays in sleep quality doesn’t end there. It goes far beyond avoiding the afternoon caffeine-hit and midnight snacks.
Have you ever considered that certain foods might actually improve your sleep? A growing body of evidence suggests several can aid a good night's sleep, whilst others could be disrupting it.
Cues for sleep
Our body has circadian rhythms, 24-hour cycles that are part of our internal body clock. They control many of our body’s processes and functions to happen routinely across the 24-hour-cycle.
Our sleep-wake cycle is one of our circadian rhythms, where we sleep at night and are awake during the day.
Like our other circadian rhythms, it’s affected by internal components such as our hormones, as well as our environment and diet. Light is a major environmental factor affecting our sleep cycle. Lots of the compounds that work together to regulate our sleep cycle come from our diet, such as tryptophan, melatonin, calcium, magnesium and potassium. So if your nutrition is lacking, this can throw off your rhythm and affect your sleep.
There are some well known choices for a sleep-promoting diet like chamomile tea, which can improve sleep quality 3. Here are eight more surprising aspects of your diet that may help, or hinder, a good night’s rest:
- Kiwi fruit
Kiwifruits contain antioxidants and serotonin. The antioxidants may help to combat the high levels of oxidative stress seen in patients with sleep disorders 4, and the serotonin promotes sleep 5.
In a study that measured the effects of kiwifruits on sleep quality, 24 participants were asked to consume 2 kiwifruits an hour before bedtime every night, for 4 weeks. Sleep onset, sleep duration, and waking time after sleep onset were measured. After just 4 weeks these had all significantly improved. The participants' sleep quality improved by 42.4%, and sleep onset latency (the time it takes to fall asleep) improved by 35.4% 4.
- Tart cherries
A few studies have shown that tart cherries, and their juice, can promote longer and more restorative sleep 6 7 8. They may also improve the severity of insomnia, resulting in a better quality and quantity of sleep 9.
Tart cherries naturally contain an antioxidant called melatonin, which is a key regulator of your sleep cycle. They can increase melatonin in the body, explaining some of their sleep-inducing effects 8. Why take a supplement when you can get the effects naturally from a delicious fruit or juice?
Lettuce seed oil has been used to aid sleep in folk medicine for thousands of years, and lettuce has been suggested to have a sedative-hypnotic property.
We may view lettuce as a basic, watery vegetable, but it contains something useful called Lactucarium. This fluid contains the chemical compounds called lactucopicrin and lactucin which are responsible for its sedative properties.
Studies in animals have shown that lettuce can increase sleep duration and shorten the time it takes to fall asleep 10 11. The authors of one study concluded that ‘lettuce, especially romaine lettuce, is an interesting and cheap source of sleep-potentiating material’ 11.
We would need to see this replicated in human studies before anything can be confirmed. For now it’s an interesting thought that seemed to work for the Romans thousands of years ago.
- Avoid saturated fat
We know that saturated fat is worth avoiding for our heart health, now add to this a better night's sleep.
In one study from the Journal of Clinical Sleep Medicine, researchers found that intake of saturated fat was associated with lighter, less restorative sleep and more sleep arousals during the night 12.
Another study looking at 459 postmenopausal women found those with higher intakes of saturated fat had a lower total sleep time, suggesting that saturated fat may negatively impact our sleep 13.
Animal-derived foods, followed by processed foods, are the biggest contributors to saturated fat intake in the US. Cut down on the animal foods to lower your saturated fat, and you may be rewarded with better rest alongside a healthier heart.
A lack of fiber in the diet may negatively impact sleep quality, as fiber consumption has been associated with deeper, more restorative sleep and fewer sleep arousals 12.
This may be because fiber feeds our gut microbiome, which can in turn affect our sleep patterns 14.
- Foods high in tryptophan
Tryptophan is an amino acid famous for its sleep-inducing effects. It’s an essential amino acid, meaning the body can’t produce it so we must get it from our diet.
Several foods are high in tryptophan, including walnuts, leafy greens, sunflower seeds, pumpkins seeds, mushrooms, and peas. High carbohydrate diets can increase tryptophan in the brain, promoting sleep (this is focusing on carbohydrates found in healthy foods: vegetables, fruits, and whole grains, not refined carbohydrates like chips, white bread, and fries) 15.
- Foods high in vitamin C
You may know that vitamin C is important for the immune system, what might surprise you is its role in sleep.
One study took data from over five-thousand people in the National Health and Nutrition Examination Survey, and looked at the intake of various nutrients and their associations with sleep duration. The researchers found that vitamin C was the largest contributor to sleep variance. Less vitamin C was consumed by short sleepers of 5-6 hours a night, whilst long sleepers had higher intakes of vitamin C in their diet 16.
An important function of sleep is to move new memories into your long-term memory store, and a lack of sleep can impair our memory functions. Vitamin C has the ability to protect the brain against memory loss caused by sleep deprivation 17.
You can find Vitamin C in citrus fruits and most vegetables, such as tomatoes, cruciferous vegetables, and peppers. Increasing your intake of these may help with a good night’s sleep, and to keep your memory intact 18.
Citrus fruits are also high in potassium and cruciferous vegetables are high in magnesium which are both crucial for sleep.
- Make sure you’re getting enough vitamin D
Vitamin D, the sunshine vitamin, is crucial for the absorption of calcium. It’s made by the body when sunshine is present, and can also be obtained from the diet 19.
If you’re struggling to sleep, vitamin D may be an important one to think about, as a deficiency is associated with poor sleep quality, short sleep duration, and sleepiness 20. It’s a worldwide health concern, and 24% of the US population have insufficient levels of vitamin D 21.
Dietary sources of vitamin D include mushrooms and fortified foods such as plant milks, orange juice, and breakfast grains and cereals 22. Many scientific reviews on vitamin D comment on the difficulty of obtaining enough vitamin D in the diet and suggest supplementation of vitamin D, speak to a doctor about this first 22.
The role of vitamin D in sleep is not fully understood, it could be to do with increased inflammation and oxidative stress when a deficiency is present, which negatively affects sleep 23.
The Bottom Line
It’s no coincidence that the same diet that prevents disease is also important for sleep; one that promotes fruits, vegetables, and whole grains, and limits saturated fat intake.
These foods give the body what it needs to thrive. Consuming a wide variety of plant foods will ensure you get all the nutrients and fiber you need to optimize your diet for sleep.
Making space for certain foods like tart cherries, kiwifruits, and citrus fruits may have further benefits for sleep beyond the overall dietary pattern.
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