What is commonly called the Welsh Carol starts with the words ‘Awake Were They Only, Those Shepherds So Lonely‘.
I’ve been listening to it on a Christmas album by Linda Ronstadt that was released back in 2000.

The Lyrics:
Awake were they only,
Those shepherds so lonely,
On guard in that silence profound;
When colour had faded,
When night-time had shaded
Their senses from sight and from sound.

Lo, then broke a wonder,
Then drifted asunder
The veils from the splendour of God;
When light from the Holy
Came down to the lowly
And heav’n to the earth that they trod.

May light now enfold us,
O Lord, for behold us
Like shepherds, from tumult withdrawn;
Nor hearing, nor seeing,
All other care fleeing,
We wait the ineffable dawn.

O spirit all-knowing,
Thou source overflowing,
O move in the darkness around,
That sight may be in us,
True hearing to win us
Glad tidings where Christ may be found.