Milk contains tryptophan, an amino acid that brings out the neurotransmitter serotonin.
This produces the hormone melatonin, which is what helps you sleep. However, you’d need to drink lots of milk to get results. More likely, incorporating it into a fixed routine helps your brain wind down.
Despite this, there’s more to drinking milk than meets the eye, especially when it comes to helping us sleep. The psychological aspects of consumption are what make milk a sleeping agent.
However, from a neurochemical perspective, drinking milk can be detrimental.
Does Drinking Warm Milk Help You Sleep Better?
It’s theorized that drinking warm milk before bed helps you sleep better. Milk contains tryptophan, an essential amino acid that helps the body maintain the following:
A neurotransmitter brought out by tryptophan is serotonin, which produces melatonin. Melatonin, known as the sleep hormone, is what the brain releases into our bloodstream at night when it’s time for bed.
However, there’s no scientific evidence that a single glass of warm milk can improve sleep quality. Many scientists are skeptical about the tryptophan content in milk, as it needs to go through the blood-brain barrier to have the necessary effect.
In the presence of other amino acids, tryptophan has difficulty doing that, so it has little effect on the brain unless you drink a lot of milk at bedtime.
Eating foods rich in carbs releases insulin, which means that tryptophan has a greater effect on the brain. The effect milk has on you is dependent on the following:
- Milk consumption
- What you ate for dinner
- Resistance to insulin
So, it’s hard to determine how much of an impact warm milk has on the average person’s sleep.
Is Drinking Warm Milk Before Bed Bad?
Drinking milk before bed is not inherently bad.
The Journal of Medical Food found that the tryptophan content in milk leads to a longer and higher sleep quality. Studies don’t show the specific kind of sleep affected by pre-bedtime milk consumption.
Tryptophan only affects the first phase of our sleep, known as non-REM sleep. Non-REM sleep is considered light sleep and lasts 30-60 minutes.
Meanwhile, REM (rapid eye movement) sleep is deep sleep, and it’s the phase in which we dream and our bodies experience temporary muscle paralysis.
According to Brain Research, tryptophan may reduce REM sleep. REM sleep is an important sleeping phase because it is during REM sleep that our mind:
- Stores memories
- Regulates our mood
- Supports neuroplasticity
- Learning new skills
- Regulates stress responses
Without enough REM sleep, we:
- Become irritable
- Feel drowsy during the day
- Experience memory problems
- Have trouble completing tasks
Drinking milk before bed can help you fall asleep faster because tryptophan accelerates and amplifies non-REM sleep. However, it comes at the cost of shorter REM sleep cycles.
For this reason, sleep experts recommend that you only drink warm milk when you’re sure you’ll sleep for many hours. That way, you’ll fall asleep faster, have a better non-REM sleep phase, and cycle through enough REM stages to get a good night’s rest.
Why Does Warm Milk Make You Tired?
Many sleep experts say that warm milk makes you sleepy because it promotes the production of melatonin, the sleep hormone.
According to Neurological Research, melatonin improves the quality and duration of sleep so that it can be used as an alternative treatment for those with sleep disorders.
There are theories by sleep experts that state that the psychological association we form with warm milk forms patterns in our minds that make it easier to sleep.
Routine and Conditioning
A consistent sleep schedule, rather than milk, helps people sleep.
A consistent nighttime routine can help you fall asleep faster because your brain associates your behavior with bedtime due to classical conditioning.
Just as Pavlov’s dogs would salivate after hearing a bell, people get sleepy after drinking milk because they routinely drink it before falling asleep.
This theory suggests that we feel sleepy after drinking a warm glass of milk because our brain associates it with bedtime.
Warmth and Serotonin
Another theory is that the warmth people feel after drinking milk produces a calming effect that helps people sleep easier. You’ll fall asleep much faster if you feel nice and warm inside.
Warm liquids, such as herbal teas and hot chocolate, increase serotonin, and that’s why many feel calm when drinking these warm beverages. This theory suggests that it doesn’t matter what you drink at night, so long as it calms you and isn’t alcohol.
Does Cold Milk Help You Sleep?
There’s no research comparing the effects of warm and cold milk when it comes to helping people sleep. However, warm beverages tend to have a calming effect on people.
Sleep experts (who believe that a consistent routine is the most important part of improving sleep quality) say that it doesn’t matter what you drink before going to bed.
As long as your drink of choice is incorporated into your nighttime routine, your brain will form the necessary association. The only exceptions to this rule are alcohol and coffee. Alcohol disrupts your sleep cycle, and coffee keeps you awake.
So, it doesn’t matter if the milk you drink is cold or hot; you must drink it consistently before bed.
How Long Does It Take for Warm Milk to Make You Sleepy?
Because studies examining how milk affects our sleep are inconclusive, it’s hard to tell how long it takes for milk to put you to sleep. It’s different for everyone, and results may vary on different days.
The effects the tryptophan content in milk has on you are dependent on other factors. These include how carb-rich your dinner was and how much milk you consumed.
Other things have little to do with milk that may affect how long it takes for you to sleep, such as:
- Physical activity
- Stress levels
- Sleeping disorders
- Hormonal imbalance
If you take longer than 30 minutes to fall asleep, you may have a sleep disorder that a glass of milk won’t resolve. People usually take 10-30 minutes to fall asleep, and any longer than that indicates a problem.
Does Lactose-Free Warm Milk Help You Sleep?
Lactose-free warm milk may help you sleep, but not because of the tryptophan content. Even though lactose-free milk contains many nutrients, whole milk contains the most tryptophan.
Even so, drinking lactose-free milk can help you sleep if drinking warm beverages calms you and makes you sleepy.
The things most likely to help you sleep include:
- Feeling of warmth and comfort
- Regular nighttime routine
This isn’t due to the type of milk itself.
Does Warm Milk with Honey Help You Sleep?
According to Clinical Nutrition ESPEN, warm milk with honey improved the sleep status of individuals after drinking the mixture for three consecutive days.
The people in the study drank milk with honey twice a day. Despite no changes in their sleep patterns after the first night, researchers found that they slept better after day 3.
Honey is a sweet substance, and sweet things promote serotonin release. Serotonin is a precursor to melatonin, so it makes sense that milk with honey helps people fall asleep.