According to the American Institute of Stress, Americans are one of the most stressed-out people in the world. The current stress level experienced by Americans is 20 percentage points higher than the global average. The Phillips 2019 global sleep survey revealed that 62% of adults around the world say they don’t sleep as well as they’d like, and more than four in 10 say their sleep has gotten worse in the past 5 years.

Can dairy help to calm a troubled population? Specific nutrients in milk may actually help ease stress and promote sleep.

The sleep-inducing benefits of milk

Warm milk has been used to induce sleep for centuries. Milk contains a wide range of nutrients that can ease stress and promote sleep, including tryptophan, melatonin, lactose, phospholipids, bioactive peptides, magnesium, zinc, B-vitamins, and vitamin D.

Tryptophan is the indirect precursor of serotonin, a relaxing neurotransmitter that is used for melatonin (a sleep supporting hormone) production. Melatonin is a neurohormone produced from tryptophan by the pineal gland, and has a role in regulating circadian rhythm and sleep.

Studies have shown that cow’s milk harvested at night (night milk) contains higher amounts of tryptophan and melatonin. Milk may actually be nature’s sleep potion.

Milk sugars and other carbohydrates act on serotonin in the brain, so a glass of milk with a graham cracker will provide more glucose to the brain. Even the act of sipping warm milk can have a soothing psychological effect.

Milk is a rich source of B-vitamins. Vitamin B6 helps to raise serotoni levels. One study, “The Effect of 90-Day Administration of a High Dose Vitamin B-Complex on Work Stress,” found that a group that was treated with B-vitamins reported significantly lower personal strain and reduction in confusion and depressed/dejected mood after 12 weeks. Vitamin D supports serotonin synthesis and helps to preserve serotonin.

Gut health is intrinsically linked to levels of the stress hormone cortisol in the body. Lysine and arginine are two amino acids present in milk and yogurt that work together to decrease anxiety and lower cortisol levels. In addition, probiotics in yogurt may help reduce anxiety. Researchers hypothesize that the bacteria in yogurt help relieve stress by reducing activity in the insula, or the region of the brain responsible for emotion. 

Bioactive dairy fractions

Alpha-casozepine, sold under the brand name Lactium, is a bioactive peptide found in milk that has been shown to lower blood pressure and reduce cortisol levels. It is a hydrolyzed milk protein and is hypoallergenic. Unlike benzodiazepines, it has no side effects and is not addictive.

Milk phospholipids are integral for keeping our brains healthy and improving our response to stress. In contrast to single-source phospholipids, Nutiani Phospholipids, a milk fat globule membrane (MFGM) rich powder, are comprehensive in their composition. Encompassing a spectrum of major phospholipids and sphingolipids, these phospholipids are available to food companies as Phosphatidylserine, Phosphatidylcholine, Phosphatidylethanolamine, Phosphatidylinositol and Sphingomyelin, with each of these components occurring in proportions similar to those found in the human brain. A recent study, “The Effect of Supplementation with Milk Fat Globule Membranes on Psychological Health: A Randomized Clinical Trial in Healthy Adults with Moderate Stress,” found that Nutiani Phospholipids consumed daily for 12 weeks resulted in lower stress scores than a placebo group. 

“While celebrated and well researched in infant nutrition for a number of years, MFGM sourced phospholipids are an unsung hero for adult nutrition. Fonterra is proud to champion scientific research proving the benefits of broad-spectrum phospholipid supplementation across all life stages,” said Peyton Rudy, global marketing manager, Fonterra.

Whey protein derived from cow’s milk is also a good source of tryptophan. A recent study, “The Effect of a Whey-Protein and Galacto-Oligosaccharides Based Product on Parameters of Sleep Quality, Stress, and Gut Microbiota in Apparently Healthy Adults with Moderate Sleep Disturbances: A Randomized Controlled Cross-Over Study,” found that in a select group of participants, the dairy product reduced salivary cortisol and stimulated Bifidobacterium, which possibly is important for sleep improvement.

Alpha-lactalbumin is a milk protein that increases plasma tryptophan availability and improves morning alertness. A 2023 study found that consuming alpha lactalbumin before sleep improved sleep quality in a group of female rugby athletes. 

I can testify to the fact that seniors can find getting a good night’s sleep challenging. The nutrients in milk are the same, whether consumed hot or cold, but a cup of warm milk, with a dash of chocolate syrup or vanilla extract, has soothed this senior to sleep many a night.