People working in so-called “green buildings” work more efficiently during the day and sleep more soundly at night, according to a groundbreaking new study.

Green buildings have better ventilation, lighting and heat controls, which researchers say can improve employees’ performance and even boost their productivity by thousands of dollars every year. The study, which was published in the journal Building and Environment, also concluded that aesthetically pleasing offices can make employees happier and more hard-working.

Researchers analyzed employees of certified green buildings in five U.S. cities and compared them with workers at different offices owned by the same companies. 

“We saw higher cognitive function scores for workers in green certified buildings, compared to their counterparts in buildings that were still high performing, but which had not achieved green certification,” said Joseph Allen from the Harvard TH Chan School of Public Health in the US.

Via a standard test that uses a Sims-like computer game to assess one’s ability to think and plan, workers in green buildings scored over 25 percent higher.

“The tool assesses complex decision-making performance, which mimics the real-world decision making that all of us encounter every day in our normal work routine,” said Allen.

The sleep quality of workers in different buildings was also analyzed using watches with sensors that measured length of sleep, as well as sleep interruptions. Those working in green buildings scored six percent higher sleep scores.

“I think this is one of the most provocative findings in the study - it suggests that buildings impact us after the eight hours we are in there for our work day.”

Green office workers also reported 30 percent fewer “sick building syndrome” symptoms, which include headaches as well as eye and respiratory irritation.

“There is absolutely a psychological as well as a physiological impact of being in better buildings,” said Allen, “and I think they are both critically important.”

h/t The Guardian.