The Welsh Christmas tradition involving early-morning church services with carols is called Plygain.
A Plygain service traditionally begins between 3 and 6 a.m. on Christmas morning. Worshippers gather in a dark church, historically carrying candles or joining a torchlit procession. The name may derive from the Latin pullicantio, referring to cockcrow, although a Welsh origin connected with bending in prayer has also been proposed.
Plygain carols are distinctive long Welsh religious poems, often sung in three- or four-part harmony. Unlike many modern English Christmas songs, they commonly trace Christian history beyond the Nativity, including the Crucifixion and Resurrection. Traditionally, singers performed without repeating a carol during the same service, and men often sang the parts.
The custom declined during the Victorian period as family-centred Christmas celebrations became more prominent, but it survived in parts of Wales, especially the northeast, and has experienced a revival. It is not the same as an eisteddfod, a Welsh cultural competition, or Noson Lawen, a Welsh informal entertainment evening.