When dealing with a restless child at bedtime, a parent may serve up a glass of warm milk. But from a physiological perspective, does the warm milk actually cause one nod off?
Proponents of this myth may claim that milk contains tryptophan, which causes sleepiness. However tryptophan can’t cross the blood-brain barrier unless insulin is present, experts noted. So you’d also have to ingest carbohydrates with the milk to raise your blood sugar to absorb the tryptophan. And even if you do, the amount of tryptophan in milk is so small it has virtually no effect.
“What we’re finding actually is that the milk does not have enough tryptophan to help a person fall asleep,” says Dr. Sudeepta Varma, a board-certified psychiatrist and clinical assistant professor of psychiatry at NYU.
The fact the milk is warm may have a soothing effect, similar to having a warm blanket or snuggling with a teddy bear.
Dr. Varma sums it up: “So while a glass of warm milk at bedtime may be comforting, there is no clear evidence to suggest it’s actually going to make you fall asleep.”
And that pretty much puts this myth to bed.