Scientists prove what mothers already knew: a glass of milk is best for a good night’s sleep

·3 min read
Cows' milk, together with a digestive enzyme called trypsin, can create a highly effective mixture of sleep-enhancing peptides
Cows' milk, together with a digestive enzyme called trypsin, can create a highly effective mixture of sleep-enhancing peptides

A warm glass of milk has long been used by parents to settle their toddlers before bed. Now new research has suggested that it is not just an old wives’ tale and the bedtime drink really does help ensure a good night’s sleep.

It is estimated that more than a third of Britons struggle to get to sleep. Sedatives such as benzodiazepines and zolpidem are commonly prescribed to treat insomnia, while sales of cannabis oils as a natural remedy have surged over the past year.

However, many of these sedatives come with side-effects including memory problems, confusion and muscle weakness, as well as being highly addictive for some users.

The medications work by activating the GABA receptor, a protein in the brain that suppresses nerve signalling and slows brain activity.

In an attempt to find alternatives, scientists, funded by the National Natural Science Foundation of China, discovered that naturally sourced peptides in milk caused the same effect of drowsiness by binding the GABA receptor.

Cow’s milk contains tryptophan and other peptides called casein tryptic hydrolysate (CTH) that relieve stress and encourage sleep. Together with a digestive enzyme called trypsin, they create a highly effective mixture of sleep-enhancing peptides.

Within this milky mixture, scientists discovered that a specific peptide, known as α-casozepine, could be responsible for causing these effects.

The team also identified other bioactive properties released from the CTH mixture when the milk was swallowed and digested.

While observing the digestion process, the scientists virtually screened the peptides when they bound to the GABA receptor and the researchers watched for their ability to cross the blood-brain barrier.

In tests upon mice, the researchers observed a specific natural peptide called YPVEPF, which increased the number of mice that fell asleep quickly by about 25 per cent, while improving their sleep duration by more than a staggering 400 per cent, compared to the control group.

This promising peptide confirmed that other properties of the CTH mixture should be explored to enhance sleep using natural pathways instead of medicated ones, the scientists said.

The study’s findings were published in the ACS’ Journal of Agricultural and Food Chemistry.

Rhiannon Lambert, Harley Street nutritionist, said the findings showed the importance of diet and nutrition in producing the hormones that regulate our circadian rhythms and sleeping patterns.

“A large amount of the happy hormone serotonin is produced in our gut – and much of it comes from our diets. Serotonin has an active role in the production of melatonin, which regulates our sleeping patterns,” she told the Telegraph.

“It’s derived from carbohydrates and an amino acid which forms a protein called tryptophan – so certain carbohydrates and tryptophan-rich foods absolutely have a role to play in promoting better sleep.

“As a result, a lot of the time I find that people who are under-eating or who follow a low-carb or low-energy diet don’t sleep as well or find it harder to switch off. Many people just aren’t aware of the role food and gut health has to play in regulating sleep, and the fact that food – and carbohydrates in particular – can be a vital sleep aid.”

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