The tradition of lighting Christmas trees with candles has been around for centuries, but it was only recently replaced by electric lights. Before the advent of electricity, people had to rely on firelight or face total darkness during the long winter nights.
This practice made many feel uneasy and vulnerable, especially in rural areas where outsiders were a common threat. The fear of being attacked by someone lurking outside one’s home was ever-present.
In Robert Eggers’s horror film Nosferatu, this era is recreated to emphasize the darkness and isolation of 19th-century Europe. Despite the festive atmosphere of a candlelit Christmas tree, the overall tone of the film remains somber and unsettling.
Source: https://www.thefp.com/p/villains-evil-hollywood-nosferatu-robert-eggers