A recurring theme I hear my entrepreneur colleagues discuss is how little they sleep. It may sound like ordinary complaining, but most of the time they’re wearing their lack of sleep as a badge of honor. They rationalize that the less they sleep, the more productive they are, the more they consider themselves some kind of business warrior. Hah! As a brain scientist, this makes me laugh.

We’ve all heard why sleep is good: it builds energy, increases memory, stimulates creativity. But these abstract ideas never convinced me to hit the sack, and I suspect they’ve failed to convince other Type A personalities trying to fit as much productivity as humanly possible into each day.

So let’s get down to the concrete, indisputable facts about sleep. First, we know that we can’t live without it. Next to air and water, sleep is the most important thing to our survival. We can live for approximately 15 minutes without air, 9 days without water, or an agonizing 21 days without food. But we can’t last much more than 10 days without sleep. Randy Gardner holds the official record; the 17-year old made it a whopping 264 sleepless hours (approximately 11 days) without dying.

Most of us aren’t interested in going to that extreme, but what happens when the amount of sleep we get daily is minimized? Unsurprisingly, it causes all sorts of short-term and long-term problems, and new research is shedding some light on why.

Our bodies leverage something called the lymphatic system to push out toxins. The lymphatic system mimics the flow of blood and oxygen throughout our entire body and works to remove waste and byproducts as we consume energy. The lymphatic system flows throughout the entire body with one exception: the brain.

The brain is so tightly packed in our skulls and the real estate up there is simply too expensive to accommodate a large structure like a lymphatic system. For years, scientists were convinced the brain was a tremendous recycler of waste: rather than dispose of it like the rest of our bodies, we mysteriously reused and repurposed waste byproducts as if the brain subscribed to composting. But that process itself would be expensive in terms of both energy and space, and that theory has never been proven.

Scientists have recently discovered a far simpler answer to the waste dilemma: sleep. We know that when we sleep, our brains cycle through different stages of light and deep sleep. We have long associated these with dreams and long-term memory but no one really knew what was physically happening in the brain during these sleep cycles. But this year, Danish scientists testing mice found that as animals sleep, their brains actually compress and grow smaller. As we move into deeper sleep stages, various parts of our brain shut down, and that reduced power consumption reduces the swelling across our neurons. As that happens, our cerebrospinal fluid—the stuff we thought was there solely to protect our brains from hitting our skulls—actually flows into and throughout the brain. We cycle through sleep stages roughly every 45 minutes and as we cycle, the cerebral fluid flows in and out, in and out, gently cleaning our brains of toxins. This is evolution at its finest: the brain takes a shot at two birds, using the cerebral fluid both for protection and for cleaning.

It is the same concept used in the mouth, an external area where the lymphatic system can’t reach: the enzymes in saliva act as mouthwash, constantly cleansing our teeth, tongue, and gums. But the mouthwash of the skull cannot fit into the cavities of our inner brain because our neurons are too tightly packed. That’s where sleep comes in, by reducing the brain’s size to make room for the mental floss. In this way, the process of sleep acts as a cleansing agent for the brain’s toxins.

Without any sleep, toxins build up and kill us after about 200 hours or so. In the case of limited sleep, these toxins kill us over time. Lack of sleep is linked to far too many issues to list—chronic fatigue, confusion, poor decision-making, irritability, headaches, weight gain, depression, heart disease, the list goes on and on. Sleep deprivation has also been linked to Alzheimer’s and other long-term degenerative brain diseases. Given we are talking about constipation of the brain, the negatives should come as no surprise.

Doctors are in agreement on the precise level of sleep needed—at least 7 hours is necessaryper night. And sleep deprivation compounds, so every night counts. None of us are immune, no matter how busy or important you are. So the next time you start thinking about how to better yourself, improve productivity, or stay ahead of the herd, lose the bravado and just go to bed.

Published in collaboration with LinkedIn

Author: Jeff Stibel is the Chairman & CEO of Dun & Bradstreet Credibility Corporation.

Image: A stockbroker looks at stock index numbers on his computer screen at a brokerage firm in Mumbai August 6, 2007. REUTERS/Punit Paranjpe