[header] How to sleep on a freezing night [title] Drink a glass of hot milk. [step] Milk contains calcium, which helps relax you and is good for your shivering bones. The warmth of the drink warms your cockles up. 
If you're not like me, and you don't like milk on it's own, then add something to it, such as cocoa powder, making hot chocolate. Do not include any sugar to it, though.