Get A Good Night’s Sleep: Diet Fact




Diet is an important factor that can determine whether or not you get a good nights’ sleep, and often sleep problems can be eliminated by simple dietary changes. Many of the sleeping medications that are available come with poor results and significant risks, some of which were only recently identified, so changes to your diet are a simpler and less invasive alternative.

The notion that certain foods may induce restful sleep has been accepted for many generations. Often we’ve heard that a cup of hot milk may help, which surprisingly has some merit. It has only been in the past ten years that a determination of which foods and most importantly, which combination of foods has been proven to be efficacious in the treatment of chronic insomnia.

What promotes good sleep?

There are three substances that are key to understanding how nutrition can affect the brain chemistry that promotes good sleep:

  • Tryptophan,
  • Serotonin, and
  • Melatonin

What is tryptophan? All protein foods are composed of amino acids and tryptophan is one of them. It is the rarest of the amino acids, and is found in foods like turkey, steak, chicken and pumpkinseeds, and to a lesser extent in peanuts, sunflower seeds, beans and milk. Tryptophan is important because when it reaches the brain, it converts to an important chemical called serotonin.

What is serotonin? You may have heard of serotonin because of its connection to drugs such as Prozac, which are known as selective serotonin reuptake inhibitors (SSRIs). Serotonin is actually a chemical that carries messages between brain cells (neurones) and other cells. Decreased serotonin levels can lead to anxiety, depression, and increased cravings for carbohydrate foods. At night-time, serotonin undergoes two metabolic changes to become melatonin, the chemical that induces sleep.

What is melatonin? Melatonin is a hormone that helps to regulate the body’s circadian rhythm and promotes restful sleep. It is produced from serotonin in the evening to help us sleep.

The best way of ensuring optimal melatonin production is to sleep in as dark an environment as possible. As we have mentioned, even low amounts of ambient light will suppress the production of melatonin which will affect not only sleep but have other health consequences as well.

Eating Tryptophan-rich foods is not the entire answer

If you’re having difficulty sleeping, it’s important that you increase the level of tryptophan in your diet; however it’s not that straight forward.

Natural food source tryptophan does not exist in isolation. Tryptophan belongs to the family of amino acids all of which bind together to form proteins. Various proteins vary in how much tryptophan is present. Research by Dr Craig Hudson has determined that gourds seeds (pumpkin and marrow or squash seeds) contain one of the highest sources of tryptophan known. Eating more of these seeds, however, will not increase your brain tryptophan levels because of what is known as the ‘tryptophan paradox’ in that eating protein foods rich in tryptophan will decrease rather than increase your brain tryptophan levels.

The reason behind the Tryptophan Paradox is something called the Blood-Brain-Barrier (BBB), a shield that protects the sensitive brain from noxious substances that are in the blood whilst allowing certain nutrients into the brain. In the case of tryptophan, access to the brain happens across a transporter that recognizes the tryptophan molecule and then facilitates its absorption into the brain.

The problem with tryptophan is that it shares this transport site with other amino acids which are far more abundant and better able to “stick” to the transporter. The result is that a high protein food contains tryptophan but also contains many more of the other amino acids that will out-compete tryptophan for access to the brain transporter site. Consequently, when you eat protein foods your blood tryptophan levels go up but your brain levels go down. Competition between tryptophan and other amino acids at the BBB transport site is the reason behind the tryptophan paradox.

This is the primary reason why high-protein diets cause you to become more anxious, irritable and experience difficulty sleeping.

Innovations that help us sleep – Zenbev

For more than a decade the Tryptophan Paradox effectively eliminated the use of protein source tryptophan as a way of building brain tryptophan levels, however Dr Hudson discovered that you could allow high protein source tryptophan to access the brain by suppressing the blood levels of the other competing amino acids by combining it with a carbohydrate food.

The addition of a carbohydrate is important because it increases serum insulin levels and when insulin is released into the bloodstream, it suppresses all amino acid levels except for tryptophan. Because it is important that just the right amounts of carbohydrate are combined with the protein-source tryptophan he developed a food – Zenbev, which is taken with milk in the evening and has been shown to aid a good night’s sleep as it gives the body the building blocks it needs to produce melatonin.

See Resources for more information about Zenbev

Food Combinations that Promote Sleep

Turkey and roast potatoes is an example of a protein-carbohydrate combination that is thought to make us sleepy. We only need to think of Christmas dinner and its sleepy aftermath as an example. Turkey is indeed very rich in tryptophan but if eaten on its own, brain tryptophan levels will decrease as explained earlier. It is actually the high-carbohydrate foods eaten with the turkey (potatoes, Brussels sprouts, Christmas pudding) that have the effect of getting the tryptophan into the brain.

Choosing the right protein food is actually quite challenging initially. Many people are aware that milk is rich in tryptophan but may not be aware of how tryptophan is required to induce sleep. Milk contains approximately 40mg of tryptophan per glass. In chronic insomnia people may require 2000mg or more of tryptophan, which would require rapidly drinking 50 glasses of milk to get the required tryptophan, however it would result in their tryptophan levels decreasing!

So it’s important to combine protein-rich foods with a fairly high glycaemic index carbohydrate to increase insulin levels and increase tryptophan-serotonin-melatonin levels.

High Glycaemic Index Carbohydrates

Some carbohydrates, referred to as high glycaemic carbohydrates, break down quickly into glucose in the body, inducing a rapid rise in insulin levels which speeds the increase in brain tryptophan levels.

Normally it is advisable to avoid high glycaemic carbohydrates since it is usually better to have a lower, more gradual increase in insulin levels, especially for those who suffer from diabetes or for weight control. However because the ideal way of eating your way to better sleep is consuming a high glycaemic carbohydrate combined with a high protein food, it’s important to know the best combinations in order to avoid weight-gain . That way, the carbohydrate has a chance to shunt the competing amino acids away in favour of tryptophan, allowing it to get into the brain to trigger sleep.

Best food sources of tryptophan

best food sources of tryptophan

Best combinations

best combinations

Other Benefits? Appetite Regulation with Tryptophan-rich Foods

When someone is depressed they crave carbohydrate foods, and the tryptophan paradox may explain why. In a depressed phase, the brain inherently recognizes the paucity of serotonin and compensatory mechanisms take place to drive the tryptophan brain levels up. Eating carbohydrates increases insulin levels which, in turn allow tryptophan access to the transport sites into the brain. When we are satiated with tryptophan we no longer crave carbohydrates and we inherently choose a balanced diet. This knowledge can be used to manage your diet to reduce carbohydrate cravings and maintain weight.

Be careful if taking melatonin

Why not avoid all of this mess and just take melatonin supplements. Although they may be beneficial for short periods of time such as treating jet lag when crossing time zones, long-term, high dosage melatonin is not recommended. It may disrupt your own natural melatonin production and potentially suppress your ability to produce this important hormone.

Aside from being an unlicensed medicinal product in the UK, you should also be wary of melatonin because it has a very short half life, which is the time it takes to metabolise and rid itself of half the circulating amount. This short half life of only 30-50 minutes means that its effect is lost in the presence of light. And finding the right dosage is also difficult. Too little and you may wake up in the middle of the night, and too much and you may feel hungover the next day.

Cherries can promote good sleep

Cherry juice has been shown in studies to help people sleep longer due to its ability to help the body produce melatonin. In a study it was found that drinking 30ml of a sour cherry juice twice a day led to an increase in circulating melatonin, providing improvements in sleep amongst healthy adults. The study used Montmorency cherry juice but if you can’t find this variety in health food stores, Acerola cherry juice is also a sour variety which may be as effective.

(Dr Glyn Howatson, School of Life Sciences at Northumbria University Nov 11/ Dr Wilfred Pigeon, University of Rochester in New York, Journal of Medicinal Food)

What can hinder sleep?


The ability of caffeine to hinder sleep is well documented. It stimulates the nervous system, increases alertness and wards off sleepiness. Caffeine is found in: coffee, tea, chocolate, cola and energy drinks, so all of these are to be avoided, especially in the afternoon and evening.


Despite alcohol being used to ‘knock you out’ after a long day, supposedly putting you into a drowsy stupor so that you sleep like a log till morning, this is not actually the case. Alcohol may seem to make it easier to drop off, but you are more likely to experience poor quality sleep and become dehydrated. You will also wake frequently to urinate because alcohol is a diuretic, and acts on the kidneys to make you pee more than you take in. So not only is your sleep disturbed by having to get up to urinate, as you’re urinating more you’ll start to feel dehydrated which may wake you, and as you drink water to relieve the dehydration it may cause you to get up to relieve yourself of the excess water. Alcohol in the evening can definitely hinder sleep.


Only eat a sugary snack before bed if combined with a tryptophanrich protein food.


  • Always combine a protein food with a low to medium glycaemic index carbohydrate food to optimise tryptophan levels.
  • Avoid stimulants such as caffeine and cigarettes
  • Avoid sedatives such as sleeping pills and alcohol to help you sleep. The effects are usually short-term, they can have counter effects, and sustained use can lead to dependency.
  • Do not stop taking sleep medications suddenly. The best approach is to speak to your doctor and develop a strategy to slowly wean yourself off them.
  • Avoid buying melatonin supplements from the Internet (they are only available on prescription in the UK). Taking them may disrupt your own natural melatonin production and potentially suppress your ability to produce this important hormone, ultimately making sleep problems worse.
  • Changes in diet can help you sleep but it takes a little longer than the quick fix pill. Fill in a sleep diary and note what you’ve done on days when you’ve slept well or badly.

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