My mum always told me that having a glass of warm milk before bed would help me sleep. So have innumerable magazines, books, and websites. And, even some reputable medical publications.
If milk does help you sleep, and you regularly use it for that purpose, then, that’s great. Best not to jinx it by delving into the details too deeply, so you may wish to read something else instead of this report. If it works, stick with it and good luck to you.
But, if the old remedy has never worked for you, or you’re just curious, read on.
So, does a class of warm milk really help you sleep or is the advice just an old piece of folklore?
The Tryptophan Connection
Conventional wisdom maintains that the insomnia-beating benefits of milk are due to the amino acid tryptophan. Milk does contain tryptophan and there is evidence that tryptophan can sometimes help people to get to sleep more quickly.
James Lake, MD notes in Psychology Today:
l-Tryptophan, 1 g, at bedtime reduces time to sleep onset in mild situational insomnia, and doses up to 15 g at bedtime may be necessary for severe insomnia. Case reports suggest that nighttime use of 5-HTP at 300 to 600 mg may improve mild to moderate insomnia and lessen sleep disturbances related to obstructive sleep apnea and narcolepsy.
Michael J. Breus, PhD notes on WebMD that:
Studies of tryptophan’s impact on sleep have found only one phase of sleep – the first one when you’re falling asleep – is enhanced by tryptophan. Other aspects of sleep, such as the amount of deep-sleep reached during the night, can be harmed by tryptophan, especially if it’s taken in supplemental form.
However, health experts have questioned the ability of tryptophan in milk to cross the blood-brain barrier.
Simon Young, Ph.D., a research psychologist at McGill University, notes in a 2016 Psychology Today article that “a glass of warm milk at bedtime will not raise the level of tryptophan entering your brain”.
Young discusses the claim that tryptophan in turkey can make you sleepy. He notes:
[…] tryptophan uses the same means of transport into the brain as other amino acids, and has to compete against them to cross the blood-brain barrier. As it happens, tryptophan is the least abundant amino acid. Forced to fight for access against the more common amino acids, it’s left waiting at the gate: the amount of tryptophan entering the brain decreases.
This blood-brain barrier factor applies to milk and many other foods containing tryptophan.
A 2007 New York Times health report on the supposed benefits of warm milk as a sleep-aid, concurs, noting:
To have any soporific effect, tryptophan has to cross the blood-brain barrier. And in the presence of other amino acids, it ends up fighting — largely unsuccessfully — to move across.
And, a 2016 HuffPost report that discusses whether warm milk can help you sleep asked Central Queensland University sleep expert Drew Dawson for advice on the issue:
Despite milk’s tryptophan content, Dawson says the amount present in a glass of milk is lower than what would be contained in a melatonin supplement and that, for the average person, the dose is probably too low to feel the effects.
So, given this evidence, it seems unlikely that tryptophan is the element in milk that helps you sleep.
Nevertheless, many people insist that drinking milk before bed does indeed help them sleep. So many, in fact, that the effect simply cannot be dismissed outright. Since tryptophan is not likely to be causing this benefit, what might be happening?
It may well be the comfort connection that warm milk provides that helps you drift off to sleep. I have vivid childhood memories of my mum preparing warm Milo for me and giving it to me in my “special cup” at bedtime. Just before my dad read me my nightly stories.
It’s a comforting memory that evokes feelings of safety, nurturing, and love. And, I think many people likely share such childhood memories.
So, it could well be these pleasant and comforting thoughts and memories rather than the milk itself – or its temperature – that helps you relax and nod off at bedtime.
And, of course, there is always the – often amazingly powerful – placebo effect. If you have been told from childhood that drinking warm milk helps you sleep and the idea has been reinforced over and over from many different sources in the years since then it may well actually work for you for that reason alone.
In a discussion of the placebo effect, a Harvard Medical School report notes that:
Although you may have learned later in life that there isn’t much scientific evidence to support the practice [of drinking warm milk to help you sleep], you may still sleep better after a cup of warm milk at bedtime.
In other words, the ingrained belief that the remedy will work may be self-fulfilling. It works because you believe it will work.
Can Drinking Warm Milk at Bedtime be Harmful?
And, if you are watching your diet, milk can add unwanted calories that you may not have factored in. Especially, if you load it up with a sugary chocolate additive.
But, those factors aside, there is no evidence to suggest that a nightly warm milk habit is in any way harmful. And, if it does help you get a better night’s sleep, regardless of how or why it works, then it can certainly be beneficial. Getting enough sleep is important for our overall health.
So, Is There an Ideal Bedtime Snack?
There are a great many recommendations for such sleep-inducing bedtime snacks. Many more than we can discuss in detail here.
Those who use them will often extoll their virtues and swear that they work. Some may have properties that do indeed aid sleep to varying degrees. And, many of the snacks probably work for much the same psychological and placebo factors that I describe above.
But, the health expert consensus appears to be that, if you are going to partake of a bedtime snack, foods high in carbohydrates are probably a good choice.
Michael J. Breus notes:
The trick is to eat foods high in carbohydrates because the insulin released will make it easier for tryptophan to nudge itself into the brain. And for this very reason, I recommend combining an ample dose of carbohydrate together with a small amount of protein (which contains the amino acid tryptophan) as the ideal bedtime snack.
And, Woman’s Health writer Leah Fessler reports:
Researchers from Japan’s Yamaguchi University found that eating a carbohydrate-rich snack in the evening may help reset your circadian clock. Why carbs? In the study, researchers found that insulin influences the crucial sleep-regulating gene PER2 in mice; this led them to conclude that ingredients that promote insulin secretion might also help promote healthy circadian patterns in humans. And since carbs in particular increase insulin secretion, they should also help to regularize your body’s PER2 cycles so you’re drowsy when you should be.
So, there you have it. To reiterate, if a glass of warm milk or another healthy bedtime snack helps you get to sleep, then go for it! I wish you good sleep and sweet dreams.