What does the word 'nightlight' suggest to you?  To me, it'as the forerunner of the tealight.  When I was a child, there was always a pack of Price's nightlights in the cupboard under the sink in case of a power cut (1970s, three-day week and all that).  For the writer of the book, it is something else, it is the kind of electric lights that parents leave in their baby's bedroom, or that people install in a bathroom or hallway to give a low level of light for night time use.

The Bible story is Nicodemus visiting Jesus under cover of darkness and famous story of John 3.  With links to John 1, Jesus as light in the darkness of a disordered word is easily made.

A Taize chant:

Stay with us, oh Lord Jesus, Christ, night will soon fall; then stay with us, oh Lord, Jesus Christ - lighten our darkness.

A prayer:

“Lighten our darkness, we beseech thee, O Lord, and by thy great mercy, defend us from all perils and dangers of this night.”