I doubt...

In the name of Allah, the Most Beneficient, the Most Merciful.

Still remember we used to learn about trypthophan in our Biochemistry class? In case you don't remember, it is used to make serotonin, which turns into melatonin, the 'sleepy' hormone.

But, I've found out, from this book called The Care and Feeding of Your Brain by Kenneth Giuffer, pg 114, it says something different. I'll quote the whole thing.

"Chapter 5 - Sleep: Tracking the Source of Sound and Troubled Sleep

Booster and Zappers in Foods

...

Myth: Protein

Protein-laden food contain certain amino acids that have inherent stimulant properties. All meats can keep you awake because of their high protein content.
It is a myth that meats (such as turkey) high in trypthophan make you sleepy. Although they do contain sedative-like property, the amino acids in protien foods have stronger effect of wakefulness.

Myth: Warm milk

Sorry, but scientifically, your mother was wrong. Milk is high in protein, which makes it harder to fall asleep. However, the power of suggestion may overide this face. If you associate warm milk with home and warmth, and sound, secure sleep, the expectation of a good night's sleep following a glas of warm milk can make it happen."

......................................................................................................
It is good to doubt. XD