Drinking milk may actually help you lose weight. A 2012 study observed that including milk products in weight loss diets "might accelerate weight reduction.” A glass of milk doesn’t represent a significant source of calories and shouldn’t greatly affect your sleep-wake cycle or weight.
So if a warm cup of milk before bed helps you relax, go ahead and take a sip.
For more information on milk’s nutritional makeup, check out our Carbs in Milk and Nutrition Facts guide.