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Fact about warm milk and sleep
Did You Know?
Poor quality sleep has been linked to low magnesium levels. So eating high magnesium foods like almonds may help in improving sleep quality.

Difficulty falling asleep at night? Suffering from insomnia? Well, the first thing you will be told by your family and friends is to have a warm glass of milk just before retiring to bed. The reason given is that milk is an excellent source of tryptophan, an essential amino acid that is proven to induce sleep. However, just because milk is high in tryptophan, does it mean that a glass of warm milk will cause sleepiness? Find the answers below.

Warm Milk Promotes Sleep - An Old Wives' Tale
Getting a restful good night's sleep has probably nothing to do with drinking a glass of warm milk. First of all, for any substance or medicine to induce sleep, it needs to penetrate the blood-brain barrier. This is how some of the sleeping pills available at pharmaceutical stores work; they can easily penetrate the blood-brain barrier which helps to treat sleeping disorders like insomnia.

The blood-brain barrier consists of endothelial cells that protect the brain tissues from pathogens, toxins, and even drugs that are circulating in the bloodstream. It is a filtering mechanism that keeps the brain safe from harmful substances.

When someone says that warm milk helps promote sleep, it essentially means that tryptophan present in milk enters the blood-brain barrier to cause sleepiness. Now the question is, can this happen? It sounds farfetched! This is because tryptophan, an amino acid has to compete with other amino acids such as tyrosine and isoleucine to breach the blood-brain barrier and reach the brain.

That tryptophan does not reach the brain was actually proved in a 2003 study conducted at the Massachusetts Institute of Technology and reported by the American Journal of Clinical Nutrition. The study observed that foods and dairy products that are high in proteins do not increase the uptake of tryptophan into the brain.

In short, it is extremely difficult for tryptophan to gain access to the brain. Even if it does, the amount of tryptophan that may get transported into the brain is too small to promote sleep.

Solution: Milk + Carbohydrates
The solution is to decrease the levels of other amino acids that are preventing tryptophan from crossing the blood-brain barrier. This can be achieved by increasing the production of insulin, the hormone that controls blood sugar levels. In short, insulin secretion can help in lowering the amount of amino acids, in turn allowing tryptophan to easily gain access into the brain.

To stimulate insulin production, you need to eat carbohydrate foods (such as crackers, cereals, dried fruits) since they are high in sugar. So having a snack of crackers along with milk means tryptophan does not have to fight with other amino acids as their concentration significantly reduces due to intake of carbohydrates. This ensures increased uptake of tryptophan into the brain, thereby producing a dramatic effect on your ability to sleep.

Verdict
As aforementioned, milk alone is unlikely to produce any sleep-inducing effect to make you feel drowsy. Those saying that a glass of warm milk makes them sleepy, the reason is more of psychological with no scientific evidence. So a mix of carbohydrates and proteins such as cereal-infused milk (breakfast cereals combined with milk) may help tryptophan to pass the blood-brain barrier, thereby producing a sleep-inducing effect.

So the next time you want to catch some zzzz's at night, make sure you have some carbohydrate foods along with your glass of warm milk. This combination will surely leave you feeling 'super' sleepy.

Disclaimer: The information provided in this article is solely for educating the reader. It is not intended to be a substitute for the advice of a medical expert.