This was the night that saw the children of each household committed into the protection of "Midder Mary", or Mother Mary (possible substitution for the "earth mother"?) On first glance, although this looks like a purely Christian ritual, the veneration of the Virgin Mary was a later addition to a pagan tradition. The corn and animals had to be protected. The trows grew strong and bold in winter in proportion, as the creatures of light paled and dwindled. Straws in the form of a cross were fixed to the lintels of barn and byre, so these places were sained, made holy. The most precious creatures in a croft and the most liable to corruption were the children. A special care was taken of them on Helya's Night, the twentieth of December. In Shetland, the old grandmother went round each bed and cradle and committed the young ones to the care of the Virgin Mary. "Mary Midder had de haund/Ower aboot for sleeping-baund,/Had da lass and had da wife,/Had da bairn all its life./Mary Midder had de haund,/Round da infants o'oor laund."

If the children were not protected, it was easy for the trows to steal them. What happened was this: The trows left their own offspring in the cradle, and these winter children generally grew up sick and deformed. So the people say of someone who looks permanently ill that he is trowie. December the twenty-fourth was a night specially holy and terrible. The trows, in dark hordes, lingered outside every croft. The terror of darkness was held in check by a strictly-observed ritual. The mother brought out a basin and filled it with water. The man of the house, priest-like, took three live embers from the fire and dropped them in the water. So in midwinter, the elements of fire and water were true to the tryst of purification. Helya’s night is undoubtedly the same as "Mother's Night" – a night that, wrote the 8th century monk Bede, coincided with Christmas Eve. In his account of the pagan calendar in 725 AD, the Venerable Bede wrote:

"And the very night that is sacrosanct to us, these people call modranect, that is, the mothers' night, a name bestowed, I suspect, on account of the ceremonies which they performed while watching this night through." The “mother” connection and the “watching” ceremonies of Mother’s Night seem to indicate that Helya’s Night was the same event, although overlaid with a Christian veneer.

On Helya’s Night, just as the children had once been committed to the protection of a goddess, ancestor, or the female deities known as the Disir, the ceremony became Christianised and the “mother” was naturally equated with the Virgin Mary, Christ’s mother.

But what was the ceremony? An account written in the 19th century recounts the experience of one woman who remembered her grandmother carrying out the ritual. She explained that, once the children were in bed, the old woman rose from her place by the peat fire and made her way over to the cradle where the youngest lay. Raising her hands over the slumbering infant, she spoke aloud:

"Mary Midder had de haund
Ower aboot for sleepin-baund
Had da lass an' had da wife,
Had da bairn a' its life.
Mary Midder had de haund.
Roond da infants o' wur land."

This procedure was repeated over all the children, while the grandfather sat raking the peats in the hearth. The old man was thought to have been reciting something also but, unfortunately, his softly spoken words were inaudible. As to the name, Helya strikes me as a corruption of the Old Norse heilagr meaning holy – Holy Night being an obvious later name for Christmas Eve.