When most people consider the keys to career success, they think of habits such as diligence, creativity, initiative, ambition, or simply working hard. However, one of the biggest keys to success in business is so simple and basic that it is often overlooked completely: getting a good night's sleep. Today's economy is a knowledge economy--which means that the modern professional's primary asset is his or her brain. The brain, scientists have found, can only be at its best after a good night's sleep.

Problems? Like what?

The problems caused by bad sleep are myriad. First, research has discovered that focus and attentiveness drop with poor sleep. Those who haven't slept enough are slower to finish tasks and much more likely to make mistakes. Impulsive, ill-considered decisions become more likely. In fact, it has even been found that a person suffering from severe sleep deficiency is as  mentally impaired as someone who is drunk.

In short, rather than being alert and quick-witted, someone who hasn't slept well will be an unproductive, error-prone mess, totally incapable of high performance--not exactly a recipe for success in the business world.

"...but I can operate on five hours of sleep or less"

So what about the people who insist that they, personally, can get by just fine on four or five hours of sleep? Are these folks right? Is their functionality unharmed by their sleep habits? And are they able to get more done as a result? In fact, researchers have found that this feeling is an illusion: People with sleep deficiencies are unable to accurately assess their abilities. While they may think they're being productive, in reality they are simply unaware of how many mistakes they are making.

It's a matter of quantity versus quality. While the professional who passes up sleep may technically put in more hours, his or her work will be of much worse quality. The stereotype of the highly accomplished person who gets by on just a few hours of sleep every night is not accurate at all. In fact, there are plenty of high performers who credit a large part of their success to always making sure to get a good night's sleep.

Good sleep is also needed to learn new skills. Memory, both short- and long-term, is heavily abridged by lack of sleep. Growth and improvement are thus not possible without sleep. This is a major problem for business professionals, who must continually hone their skills and pick up new abilities if they want to advance.

A true emotional roller coaster

The damage incurred by poor sleep extends also to the emotions. People who sleep poorly will be irritable and short-fused. Of course, no office needs someone who lashes out in anger or frustration at others. Instead of being balanced and in control emotionally, a worker who doesn't sleep enough will be erratic, out-of-control, and incapable of playing an effective part in a team. Emotionally unbalanced people also make for terrible candidates for promotions, since a true leader must be calm and fully in command of his or her feelings.

Bodily health is also greatly affected by sleep. While obviously important in its own right, good health is also a key factor in achieving career success. Over the long term, sleeping poorly raises the risks of many harmful conditions, including diabetes, heart disease, high blood pressure, depression, and stroke. The strength of the immune system also depends upon a healthy sleep cycle. Ultimately, chronic bad sleep is likely to shorten a person's life span.

Gotta catch them Zs

Those who have not been in the habit of sleeping well should do everything they can to modify their habits. Most people will be able to get quality sleep every night simply by following a few basic rules--such as going to bed and waking up at the same time every day, avoiding bright-screened electronics in the evening, using alcohol and caffeine only in moderation, avoiding naps, and exercising. People who still struggle to sleep normally may have a more serious sleep dysfunction and should see a sleep medicine specialist.

For everyone else, the goal should simply be to sleep in a more normal, healthy manner. While the temptation to burn the candle at both ends will always be present, doing so is almost never the right decision. A disrupted sleep pattern is sure to do serious harm to a professional's career, since sleep and career success are so intimately connected.