Can warm milk help you sleep?

Peter Lemon, protein expert and professor at the University of Western Ontario, Canada, replies: There is some validity to the old trick of drinking a warm glass of milk before you go to bed to help facilitate sleep. This is due mostly to milk's plentiful store of the amino acid tryptophan. Once tryptophan reaches your brain, it boosts production of serotonin, a neurotransmitter that helps you sleep. Milk contains about 112 milligrams of tryptophan per eight-ounce glass.
Because carbohydrates also increase serotonin production - which is why you may feel sleepy after a big plate of pasta - the carbs in milk also help you to drift off.
Finally, the warmth of the milk can provide a feeling of comfort, whereas cold fluids often deliver a jolt to your system.
Tryptophan can't be bought in supplement form and there's no difference in levels in skimmed milk and whole fat milk so always choose the pint of skimmed milk.