(CNN) -- While most of us are sleeping, Keith Jones spends his nights driving a truck. The Charlotte, North Carolina, resident says he doesn't mind the overnights -- the dark and the quiet time help him think. But during the day when he's at his home office filing paperwork, he says has to work in front of the window. The daylight, he says, is essential.
"I always have my windows open, or at least the blinds, when I work," Jones said. "I want to see the pretty grass in my backyard. ... It makes me happy."
Studies show there's another, more fundamental reason he wants that window. It's not just about improving your sunny disposition; scientists say it's essential to let the sunshine in for your overall health.
"Since we spend a lot of our lives in our offices, we thought understanding the impact of light was important," said Ivy Cheung, co-author of a study published this summer in the Journal of Clinical Sleep Medicine. Cheung is a doctoral candidate working in Dr. Phyllis Zee's laboratory at Northwestern University Feinberg School of Medicine.
"We already study circadian rhythm in sleep labs and find that ... light is the most important synchronizing agent for the brain and the body."
Cheung and Zee's most recent study found that workers who had a window in their office had a much better sense of health. They examined the lives of 49 people -- 27 who worked in windowless offices and 22 who worked near windows. These were people who worked a typical day shift. Participants were not told about the objectives of the study so they wouldn't be overly aware of windows in their offices.
Exposure to natural light during the workweek tended to inspire people to exercise more. Workers with a window were also better rested: Those with windows got 46 more minutes of sleep a night on average, and the ones without windows had more sleep disturbances.
Without sleep, people tend to suffer from all sorts of other problems that could hurt their performance at work such as memory loss, slower psychomotor reflexes, depression and shorter attention spans.
This lack of sleep could lead to more workplace accidents and errors.
Something as simple as daylight, the study suggests "may provide a profound way to improve office workers' productivity and health, as well as the safety of the community they work and live in."
In another recent study from Cornell University, researchers looked at the performance of nurses who worked long shifts during nonstandard hours. The study was published in the latest issue of the journal Health Environments Research and Design.
Researchers found that nurses who had access to natural light communicated better with their colleagues. They laughed more at work. They were nicer to their patients. And even their own physical health was improved: Those who saw daylight had significantly lower blood pressure. That's all in comparison with nurses who worked mostly in an environment with artificial light.
Letting natural light into a nurses' station also improved nurses' alertness. In a job where they are dealing with life or death matters, that impact can make a huge difference in patient care.
These studies add to a growing body of evidence that suggest exposure to light and dark patterns is one of the most important aspects influencing a person's natural circadian rhythm. These circadian rhythms affect everything from sleep and physical movement to mental well-being.
Other studies have looked at how daylight helps a person's overall psychological health and how students perform better in school if they see some daylight.
Cheung, who did the study involving office workers, said she hopes architects will keep this research in mind when they design new office buildings. But if you aren't lucky enough to have a window in your office, she said, you can make up for it by finding other ways to let the sunshine in.
"Get outdoors during the day," Cheung said. "Take that phone call meeting outside or make sure your lunch break is outside. Even that daylight exposure can help."