In a culture that simultaneously values productivity and distraction, many of us find ourselves cutting corners on our nightly allotment of sleep. While it's easy to view the loss of a few hours of sleep as no big deal, over time, the lost hours build up and form a sleep debt. After several days of inadequate rest, we begin thinking muddled thoughts, getting upset over trivial matters and even seeing things that aren't there. We're experiencing sleep deprivation.
There are many symptoms of sleep deprivation affecting our bodies and our brains. Sleep deprivation can be a source of domestic unhappiness, career shortcomings and potentially life-threatening situations.
So what are 10 signs you may be sleep deprived? Slap yourself in the face a few times, and then keep reading to find out.
Inability to Handle Stress
If you've been feeling stressed out lately, the circumstances you're buckling under may not be the problem -- it may be lack of sleep. Sleep deprivation wears down our normal capacity to deal with daily aggravations and challenges, such as normal rush hour traffic.
Running short on sleep seems to lower the threshold for "stress perception." When you're dead tired, having to stop at the grocery store on the way home from work may seem like an impossible task, not a routine activity.
While lack of sleep can augment stress, stress itself can lead to inadequate sleep. Studies have shown that stress hormones can be stimulating, especially in middle-aged men [source: The Franklin Institute]. This may be due to overactivation of the stress response system in later hours of the evening.
Research seems to indicate that people who sleep soundly in times of stress are more focused on tasks, while those who respond to stress by losing sleep keep their focus on their roiling emotions [source: The Franklin Institute].
But if you can't remember what it is that's stressing you out in the first place, you may be experiencing the next sign of sleep deprivation that we'll discuss.
If you've ever said, "I can't even remember the last time I got a good night's sleep," your words might be more revealing than you think. After a restless night, you may become forgetful or experience "senior moments."
Research has shown that deep sleep plays an important role in memory, because it facilitates connections between nerve cells [source: The Franklin Institute]. The less deep sleep you get, the fewer connections form between nerve cells. Both humans and animals perform worse on memory tests when deprived of sleep.
REM sleep especially aids in the formation and retention of emotional memories, which tend to be those that are most vivid to us decades down the road.
So what's the upshot? If you're facing a task that will call heavily upon a sharp memory, you may want to choose sleep over late-night preparation. For instance, a student during "finals week" shouldn't pull an all-nighter. It's better to study until feeling tired and then get plenty of sleep before the next day's test.
If you read that last sentence at least twice, you may have another common sign of sleep deprivation, which we'll discuss in the next section.
Inability to Concentrate
If you've ever dragged yourself into the office on Monday after a restless weekend and had to feign interest in a long meeting, you may be familiar with another sign of sleep deprivation -- an inability to concentrate.
Sleep-deprived subjects in studies are not only more likely to perform poorly on tests requiring concentration, but also, they're more likely to overestimate their performance. They underestimate the effects of sleep deprivation on their ability to concentrate [source: Downs].
Those effects increase as our sleep debt builds. A person getting five hours of nightly sleep for a week will perform better on tasks requiring concentration than a person who gets four hours a night for a week.
Caffeine offers a quick fix and improves concentration (for a little while, at least), with effects peaking within about an hour of consumption [source: Lieberman].
If you've noticed a change on the scale, you may have recently had a change in your sleep habits. Keep reading to learn about the connection between sleep and appetite.
Controlling caloric intake is hard enough for most people, but when their sleep-deprived brains start making demands, it can be nearly impossible to control the cravings.
Lack of sleep poses many problems to a person with an otherwise healthy diet. For one thing, the longer you're awake, the more time you have to consume calories. But lack of sleep also makes you hungry. People who've gone without sleep have higher levels of hormones that signal the body that it's time to eat and fewer hormones that signal being full, or satisfied [source: University of Chicago Medical Center].
Your brain metabolizes sugars at a slower rate when you're sleep deprived. As a result, sleep-deprived people report craving sweets and salty foods, in addition to starches. Studies have also shown a clear connection between sleep deprivation and obesity. Sleep-deprived people have double the risk of obesity when compared with those who have no trouble sleeping [source: University of Warwick].
Who would've thought that the key to losing weight might be getting more sleep?
Next, we'll consider some parallels between consuming hallucinogens and being sleep deprived.
Vision problems due to lack of sleep increase the odds of all sorts of mishaps, such as falls, car crashes or accidents on the job. After pulling an all-nighter, you may find yourself trying to make your way through a fuzzy world. Visual distortions and difficulty focusing are hazardous symptoms of sleep deprivation.
You may even start seeing things that aren't really there, detecting movement out of the corners of your eyes. It can be hard to process peripheral images and those in your direct line of sight at the same time.
Researchers attribute this to your brain's I-function, which integrates information from other parts of the brain. When neurons are deprived of regenerative sleep, they struggle to perform functions such as providing you with a perception of the world around you. As they become less efficient, they cut corners and give you images that contain most of the information you need, but not all. It's like providing only 750 pieces of a 1,000-piece jigsaw puzzle. As this image begins to differ more and more from reality, you experience severe visual distortion. If at this point, you decide to take a drive, you may also experience another sign of sleep deprivation that we'll discuss next.
One symptom of sleep deprivation could have far-reaching ramifications, even after you've rested and erased your sleep debt. The brain's prefrontal cortex is involved in judgment and impulse control, and when it's feeling the strain of sleep deprivation, your decision-making abilities feel the strain as well.
Researchers believe that REM sleep, though still far from being fully understood, helps our brains process information gained throughout the day. This important sleep stage also helps regenerate neurons in the brain.
If you miss a night's sleep, your brain hasn't had the opportunity to refresh and reorganize itself, so your ability to make good decisions suffers.
Studies have shown that sleep-deprived people are more likely to make risky decisions [source: Venkatraman]. Without sleep, you'll act aggressively in hopes of achieving short-term gains. You're more likely to bet the farm in the casino, purchase something that's outside the budget or forgo safe-sex practices. When you're well-rested, you're better able to assess when something looks risky
Of course, you won't be able to do any of those things if you can't tie your own shoes and get out the front door, as we'll learn in the next section.
Diminished Motor Skills
If life suddenly feels like a slapstick routine, it may be a sign that you need more sleep.
Researchers discovered that after you've gone a night without sleep, you're essentially operating on the same level as someone who's legally intoxicated [source: The Franklin Institute]. When you're sleep deprived, your mouth may not be able to get the words out as you try to communicate. Slurred speech, stuttering and speaking in monotone are clues that point to sleep deprivation. You may also fumble with small objects and be unsteady on your feet.
Sleep-deprived people have decreased activity in the temporal lobe of the cerebral cortex, an area of the brain that helps us process language. But another part of the brain -- the parietal region -- picks up the slack, explaining why we can speak at all when short on sleep.
Sleep deprivation also leads to slower reaction times. Studies show it affects speed before it affects accuracy (be it physical or mental). But stay awake a little longer, and you'll be neither quick nor accurate.
Next: If you've been kicked to the couch, your loved one may be refusing to accommodate your sleep deprivation.
If you and your sweetie have taken to separate bedrooms, it may have less to do with a desire for separation than with the desire of one party to get a normal night's sleep.
When sleep disorders affect one member of a household, they affect all members. Keeping late hours -- mixed with random daytime sleeping -- throws off family activity schedules, bonding time and the sleep patterns of other family members.
But a sleep-deprived person may be kicked to the couch for other reasons: moodiness, agitation and poor memory -- none of which is a trait we admire in our partners. A flagging libido may be a source of tension as well.
Chronic snoring or sleep apnea can also contribute to domestic strife. When one partner gets up feeling unrested due to a fitful night of sleep apnea, the other may feel just as fatigued from trying to sleep through the drama.
As we'll discuss next, your body has ways of telling you when you're sleep deprived.
If you've been running yourself ragged without the proper amount of sleep, your health may start providing clues that it's time to snooze.
Diabetics who experience sleep deprivation become less sensitive to insulin as the body's ability to metabolize sugar decreases [source: The Franklin Institute]. When this occurs, they may have trouble keeping otherwise controlled blood sugars in an acceptable range.
Sleep deprivation also prompts higher blood pressure, lower body temperature and a heart rate that can't quite find its rhythm.
The immune system begins to lower its defenses. The white blood cell count decreases, and the remaining white blood cells become lethargic. Rats in studies died when prevented from getting sleep, possibly as a result of immune system breakdown. While your body will forcibly shut itself down to catch up on sleep long before you could possibly die from sleep deprivation, sleeping less than four hours a night may put you at higher risk of death within the next six years [source: National Sleep Foundation].
If you're feeling giddy from lack of sleep, take a deep breath, count to 10 and read the next section.
When you're exceptionally tired but unable to get sleep, it doesn't take much to set you off. Situations that normally would be manageable may suddenly seem much more irritating. There's a good chance it's because you're sleep deprived.
One study showed that children who slept less than 10 hours in a day were 25 percent more likely to misbehave [source: The Franklin Institute].
Sleep deprivation increases your odds of experiencing feelings of depression, burnout and decreased empathy. Those who are already depressed or have other underlying mental health disorders may find those problems exacerbated by lack of sleep.
Looking for a reason to stay awake a little longer? Check out lots more information on sleep deprivation on the next page.
HowStuffWorks finds out whether people can truly ever sleep with their eyes open, as well as what the condition lagophthalmos is.
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