Not all eureka moments in history are treated equally, but the last one makes people in northern Sweden smile—literally.

Umeå sits about 185 miles north of Stockholm. During the winter, the city receives less than 60 minutes of natural daylight. “If,” a resident clarifies, “the sun shines at all.”

Lack of natural daylight can have a profound impact on the mental health of individuals and the city as a whole. To counter this, Umeå Energi launched Ljusterapi (Light Therapy), an initiative that replaced lights in 30 of the city’s bus stops with natural light frequency anti-SAD (seasonal affective disorder) light bulbs. While waiting for the bus, commuters can face the lights for a few minutes to get the psychological benefits of the natural light they miss, absorb some Vitamin D, then continue on their journey.

“We wanted to show we care about the people living here in Umeå at this dark time of the year,” said Umeå Energi CEO Göran Ernstson. “People get depressed if they don’t see light.”

The company’s initiative used a pivot in thinking to transform ordinary urban structures into extraordinary devices. Instead of taking bus shelters for granted, Umeå Energi recognized that the structures contained extra potential. By replacing the shelters’ lights with light therapy bulbs, the company doubled the functionality of the shelters—protecting commuters while also serving as mood-boosting units.

The project was executed with refreshing agility—via an advertising campaign. Instead of laboring through the usual permissions and planning bureaucracy with city agencies, Umeå Energi rented the light units normally used to backlight movie posters or cell phone promotions and asked the advertising agency to replace the bulbs and put a clear poster in the frame.

Last but not least, the company’s narrative gives the project a poetic arc. The energy source that powers the light therapy bulbs comes from stored solar energy generated by Umeå’s abundance of daylight during its long summer days.

“Everything is a part of our commitment to take responsibility for both our customers’ everyday lives [and] the environment at large,” says Umeå Energi’s marketing manager Anna Norrgård.

Assessing the impact of public projects is always tricky, but after the light therapy bulbs were installed, bus ridership in the city doubled. Soon after its launch, news and images of the project went viral with global media coverage and social media saturation; it was as close to a High Line hit as an urban infrastructure project can get.

Umeå Energi wasn’t ready, however, to reside on the list of one-hit wonders. Motivated by the passionate local response to the project and its impact on people’s daily lives, the company realized that light therapy bulbs could be put to use in a more targeted manner.

Partnering with the local Dragonskolan high school, Umeå Energi installed 140 light therapy bulbs in seven classrooms and the school’s canteen. The school’s 2,000 students aged 16 and older are particularly susceptible to seasonal depression, with the lack of sunlight layered on top of the usual teenage ennui.

“Many people in the city feel tired during the winter here in northern Sweden. For students in particular it can be hard to focus,” Stefan Andersson, one of the school’s head teachers, said in an interview with Swedish News website thelocal.se. “So far it seems to have been a success; the pupils are happier and have more energy.”

Student Benjamin Berkgnholn agreed. “It is dark when I go to school and dark when I get home from school, so it is a good idea,” he said. “For example, I came to my math class pretty tired and the lamps made me more awake and helped me work more.”

Umeå’s development of an experimental bus shelter project that became a catalyst to help students’ performance and mental health at school provides a lesson for Greater Boston. Improving the public’s mental health during dark winter months with nothing more complex than installing some new light bulbs is a relatively simple tweak of existing city and public assets. It is an opportunity that begs the question: “Why isn’t this being done here?”