You know that lack of sleep is terrible for your brain, body and productivity levels, and you've probably also heard some of the common causes for entrepreneurs' lack of adequate shut eye, from simple busyness to the impact of smartphones and even "bedtime procrastination."

What you might not have considered is how your office design is impacting your ability to get a good night's rest, and therefore put in a solid day's work the next day.

At an annual meeting of the Associated Professional Sleep Societies, Ivy Cheung, a neuroscience doctoral student at Northwestern University, and architecture professor Mohamed Boubekri, presented their findings on the effects of spending one's working days in a windowless office. The researchers compared the health of workers at 27 windowless offices and 22 who had windows in their workspaces to investigate the impact of natural light exposure. The workers in the two groups were demographically similar in other ways.

Less Light = Less Sleep

What did they find? The most startling conclusion is just how much a lack of windows affects workers' ability to get to sleep at night. Not only did the workers in offices with windows sleep on average 46 minutes more each night, they also reported higher quality sleep.

The difference in sleep patterns shocked even the authors. "We were surprised that the quality and length of sleep differences were that large,"Boubekri commented.

"The extent to which daylight exposure impacts office workers is remarkable," agreed Cheung, and it seems these effects extend beyond the end of the workday in other ways too. Those who saw less daylight at work also scored less well on measures of vitality and were less active throughout the day

Less Sleep = Less Productivity

How are those lost minutes of sleep likely to affect you? Serious sleep deprivation, previous research has shown,impairs your performance about as much as drinking alcohol, so if you wouldn't consider coming to work after downing a six-pack, you should probably think carefully before boasting about your next all nighter. But even 20 minutes of lost shut eye can have a serious impact on your ability to think clearly, and getting inadequate amounts of sleep is also linked to diminished creativity.

All in all it's a pretty ugly picture that, taken together, strongly suggests that not only should you get the recommended amount of sleep, but also ensure your work environment has adequate natural light to help you reach that goal. (If you can't swap your workspace, consider going for more walks.) Seeing the sun more will help you sleep, improve your self-control, help you de-stress, and supercharge your productivity.