For one sparkling minute each night, blinking lights from skyscrapers, tugboats, hotels, a yacht club and police cruisers send a goodnight message to sick children inside a hospital in Rhode Island.

A gesture that began with a single bike light cheering up a patient six years ago has become a nightly ritual in Providence.

Youngsters inside the Hasbro Children's Hospital wait for 8.30pm each night, when strangers flash lights from high-rise buildings and waterfront decks and parks.

The children get their own flashlights to return the message.

The hospital's resident cartoonist, Steve Brosnihan, started the phenomenon, known as Good Night Lights, and keeps expanding it by inviting more businesses and other groups to join the display.

Some bigger buildings now have automatic signs to display messages each night.