What Lack of Sleep Does to Your Mind

Sleepiness can damage your judgment, work performance, mood, and safety.

From the WebMD Archives


The people at highest risk for fatigue-related auto accidents are teenagers and young adults, especially men. Shift workers who work at night or work long or irregular hours and people with untreated sleep disorders such as sleep apnea and narcolepsy are also at high risk.

A slowed reaction time can endanger lives in other ways. In a 2009 study done with cadets at the United States Military Academy at West Point, researchers from the University of Texas in Austin found that sleep deprivation hampered information-integration. This is a function of the mind that relies heavily on split-second, gut-feeling decisions. The researchers noted that this could be a particular concern for firefighters, police officers, soldiers, and others who are often sleep deprived on the job.

The Impact of Sleepiness on Mood and Mental Health

Lack of sleep can alter your mood significantly. It causes irritability and anger and may lessen your ability to cope with stress. According to the NSF, the “walking tired” are more likely to sit and seethe in traffic jams and quarrel with other people. Sleep-deprived people polled by the NSF were also less likely than those who sleep well to exercise, eat healthfully, have sex, and engage in leisure activities because of sleepiness.

“Over time, impaired memory, mood, and other functions become a chronic way of life,” says Siebern. “In the long term, this can affect your job or relationships.”

Chronic sleepiness puts you at greater risk for depression. They are so closely linked that sleep specialists aren’t always sure which came first in their patients. “Sleep and mood affect each other,” says Verceles. “It’s not uncommon for people who don’t get enough sleep to be depressed or for people who are depressed to not sleep well enough.”

How Do You Know if Sleepiness Is a Problem?

Because individual sleep needs vary, experts say the best way to gauge whether you’re getting enough sleep is by how you feel. “You shouldn’t feel sleepy when you wake up,” says Verceles. “You should be energetic throughout the day and slowly wind down as you approach your usual bedtime.”

Krakow suggests assessing your day-to-day abilities and quality of life. “Ask yourself if your cognitive performance is where you want it to be,” he says. “Are you having conflicts with other employees or your boss over your memory, attention, or concentration -- and particularly your productivity?”

WebMD Feature Reviewed by Hansa D. Bhargava, MD on April 30, 2013



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National Sleep Foundation: “2009 Sleep in America Poll Highlights and Key Findings,” “2002 Adult Sleep Habits,” “Teens and Sleep.”

National Institute of Neurological Disorders and Stroke: “Brain Basics: Understanding Sleep.”

WebMD Feature: “The Toll of Sleep Loss in America.”

NIH National Heart, Lung and Blood Institute: “Your Guide to Healthy Sleep.”

Barry Krakow, MD, medical director, Maimonides Sleep Arts and Sciences, Ltd., Albuquerque, N.M.; author, Sound Sleep, Sound Mind: 7 Keys to Sleeping Through the Night.

Harvard Medical School: “Sleep, Performance, and Public Safety,” “Sleep, Learning, and Memory.”

Avelino Verceles, MD, assistant professor and director, sleep medicine fellowship, University of Maryland School of Medicine, Baltimore.

Allison T. Siebern, PhD, fellow, Insomnia and Behavioral Sleep Medicine Program, Stanford University School of Medicine, Sleep Medicine Center, Redwood City, Calif.

U.S. Department of Health and Human Services: “Your Guide to Healthy Sleep.”

WebMD Medical Reference: “Sleep 101.”

National Highway Traffic Safety Administration: “Drowsy Driving and Automobile Crashes.”

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