It's a curious thing that human beings, and most other animal species, are driven to regular periods of inactivity and unconsciousness. What could be less evolutionarily beneficial than a stretch of eight hours during which you can't hunt, defend yourself, or reproduce? Not to mention working on your memory improvement.
All jokes aside, the fact that we are driven to sleep is an indication that sleep has an important purpose in our biology.
And yet, the precise mechanisms of sleep remain largely mysterious. The exact reasons why we require sleep, and what happens during sleep, are areas of current research.
One thing is for certain: lack of sleep leads to an array of social, financial, and health-related costs. Indeed, the fatality rate of sleepiness-related car crashes is similar to that of driving under the influence (Goel et al 2009). What's more is that prolonged sleep deprivation leads to death for many studied species (and presumably humans) (Cirelli et al. 2008).
Despite these realities, a full 20% of adults are not getting enough sleep (Goel et al 2009). It's a common practice in our culture to praise those who can work the most and sleep the least.
However, research indicates that this attitude is misguided. Lack of sleep has important negative implications for cognition. Sleep deprivation puts pressure on your entire cognitive apparatus, and has the potential to affect your memory.
After this article, you may be convinced that a nap is in order.
What Exactly Is Sleep?
Over 85 years, an average person will sleep 250,000 hours, which is equal to 10,000 full days (Scullin et al 2015).
But what is sleep, really?
It is commonly believed that sleep is a continuous period of a complete loss of awareness. But in actuality, sleeping is not one continuous state and a sleeping person does not lose total awareness. Instead, they alternate between reduced awareness of the external world and a complete loss of consciousness (Gudberg et al 2015).
From here, sleep is typically classified into two categories. The first is non-rapid-eye-movement (NREM) sleep and the second is rapid-eye-movement (REM) sleep (Bryant et al 2004).
NREM sleep happens during the early moments of falling asleep. As the name suggests, there is little to no eye movement during NREM sleep. Dreams are rare during this stage, your body is not paralyzed as in REM sleep, and mental activity is still "thought-like" (Bryant et al 2004). This is the stage during which some people will sleep-walk.
The role of NREM sleep is to conserve energy, cool the body and brain, and promote immune function.
Following NREM sleep, a person will fall into REM sleep, where rapid eye movements can be observed. This is where the majority and the most vivid dreams occur. Your body is paralyzed, which is an adaptation to prevent you from acting out your dreams. You will periodically wake up – which some researchers feel serves as a way to survey the environment (Bryant et al 2004). These mini-awakenings are typically not remembered.
The Devastating Consequences Of Sleep Deprivation On Memory Revealed
As you sleep, you will cycle between NREM and REM sleep four to five times during the night.
By understanding our sleep patterns, it becomes evident that there is much more that happens during sleep than simply being unconscious. The broad overview given here just scratches the surface of the complex world of sleep.
For all of its complexity, sleep serves essential functions. For example, a sleep-deprived person suffers from many ailments, including:
Published on 9 years, 10 months ago
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