Christmas is commonly associated as a blissful time spent with family, a time that provides respite. In practice, this is not always the case in the run-up to Christmas and during the festive period itself. Some people experience a significant degree of stress and internal tension during December, while others struggle with a lowered mood - in extreme cases, it can even be a harbinger of developing depression. Why is it that some people find Christmas particularly joyful, while for others it can be downright... damaging?