The day after Lucia, we enter a much darker tale.
Before Lucia became the white figure with light in her hair, there was another figure in Nordic folklore, Lussi.

The night of December 13th was called Lussinatten or Lussi langnat. In old folklore, it was considered one of the darkest and most restless nights of the year, where supernatural forces could be at work. Lussi could come through the night alone or with a whole retinue of beings, and in some places it was believed that she kept an eye on whether the farm work was finished before Christmas.
This is a completely different story than the Lucia most people know today.

This evening we borrow the atmosphere from the old Lussinatt – from the darkness, the omens, the old ideas about the invisible and the human need to create warmth and protection when winter was closest to the house.

… Read more about the event at the link below.