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Dear Straight Dope:
Why does warm milk help you sleep but cold milk doesn't?
--Nicki
SDSTAFF Ken replies:
At least two things go into this:
1) Tryptophan: the same ingredient that makes everyone sleepy after
Thanksgiving dinner is present in milk.
2) Warmth: the few degrees that this drink might raise your body
temperature is often enough to trigger the slowdown response we
have on warm days.
In addition there is anecdotal evidence that the warm milk reminds
us of the time when we were infants, hence "sleep like a
baby."
Most other beverages we enjoy warm tends to have caffeine, which
inhibits sleep (coffee, hot chocolate/cocoa, leaf tea), but many
herbal teas are as good as warm milk and in fact are recommended
for the lactose-intolerant.
