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What Lack of Sleep Does to Your Mind

Sleepiness can damage your judgment, work performance, mood, and safety.
By Camille Peri
WebMD Feature

Do you often forget things that you’re sure you know? Is it hard to concentrate on complex assignments? Do you get less than six hours of sleep a night?

If so, you’re probably not getting enough sleep. That’s right; lack of sleep can hinder you from thinking clearly and keeping your emotions at an even keel. Studies show that excessive sleepiness can hurt work performance, wreak havoc on relationships, and lead to mood problems like anger and depression.

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Why Don’t People Value Sleep?

Most people who don’t get enough sleep don’t recognize the toll that it takes on their cognitive and mental health.

Many people think of sleep simply as a luxury -- a little downtime. They know they feel better when they get a good night’s sleep and worse when they don’t. But sleep actually improves learning, memory, and insight.

“You’re putting energy in the bank when you go to sleep,” says Barry Krakow, MD, medical director of Maimonides Sleep Arts and Sciences, Ltd. in Albuquerque, N.M., and author of Sound Sleep, Sound Mind: 7 Keys to Sleeping Through the Night. “On a cellular level, the body is literally repairing and restoring itself. Without it, you can’t do what you want -- physically or mentally.”

And catching up on your sleep is a bigger job than many people realize. If you get less than six hours of sleep a night for a week, for example, you’ll rack up a full night’s sleep debt -- too much to make up for with a few hours extra sleep on the weekend.

The Impact of Chronic Sleepiness

People who are sleep deprived often say they feel “foggy.” Here are three reasons.

1. Sleepiness slows down your thought processes. Scientists measuring sleepiness have found that sleep deprivation leads to lower alertness and concentration. It’s more difficult to focus and pay attention, so you’re more easily confused. This hampers your ability to perform tasks that require logical reasoning or complex thought.

Sleepiness also impairs judgment. Making decisions is more difficult because you can’t assess situations as well and pick the right behavior.

2. Excessive sleepiness impairs memory. Research suggests that the nerve connections that make our memories are strengthened during sleep. “Sleep embeds the things that we have learned and experienced over the course of the day into our short-term memory,” says Avelino Verceles, MD, assistant professor at the University of Maryland School of Medicine and director of the school’s sleep medicine fellowship.

It appears that different phases of sleep play different roles in consolidating new information into memories. If your sleep is cut short or disrupted, it interferes with these cycles.

When you’re sleepy, you may forget and misplace things often. And the inability to focus and concentrate caused by sleepiness further weakens memory. “If you’re not able to concentrate on what’s at hand, it’s not going to make it into your short-term memory and then long-term memory,” says Allison T. Siebern, PhD, a Fellow in the Insomnia and Behavioral Sleep Medicine Program at the Stanford University Sleep Medicine Center.

3. Poor sleep makes learning difficult. Sleep deprivation affects your ability to learn in two ways. Because you can’t focus as well, it’s more difficult to pick up information, so you can’t learn efficiently. It also affects memory, which is essential to learning. In children, sleepiness can lead to hyperactivity, also hampering learning. Teens may lose the focus, diligence, and memory capacity to perform well in school.

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