Wear night clothes such as pyjamas or a large T-shirt to keep you warm. Natural fibres such as wool, cotton or silk will keep you warmer than synthetic materials.
Have a warm bath just before you go to bed. This will gently warm and relax you to help you feel sleepy.
Have a warming, milky drink.
Try some exercise to get the circulation going to help keep the body warm - but don’t do vigorous exercise too close to bed time as you may feel too invigorated to sleep.
Keep the bedroom warm, but not too hot, and free from draughts.
Use several layers of bedding rather than one single layer. Layers will trap warm air and are easily removed if you get too hot.
A hot water bottle is an ideal way to keep warm once in bed. Electric blankets are ideal. Under blankets will warm the bed up before you retire for the night, while over blankets maintain a constant temperature throughout the night.