hi found this lovely piece of info on warm milk that should really help answer your question. milk contains tryptophan an amino acid that is a precursor to the sleep inducing compounds serotonin and melatonin for tryptophan to have a sedative effect it needs to enter the brain by crossing the blood-brain barrier an effective way for this to happen is to consume warm milk together with a carbohydrate (sugar). carbohydrates (sugar)and proteins in milk and heat together makes tryptophan more available to the brain this promotes the clearance of other amino acids from the bloodstream and facilitates the entry of tryptophan into the brain where it can act to produce a sedating effect. so warm over cold is still best cold is best if you have small upset stomach or some acid going round it. hope this still helps you. good luck
in the past you have advised that a glass of warm milk will help one to fall asleep. will a glass of cold milk also help. will a glass of cold milk be as effective as warm milk?