The Science of Sleep: Understanding What Happens When You Sleep

Sleep accounts for one-quarter to one-third of the human lifespan. But what exactly happens when y'all sleep?

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Before the 1950s, most people believed sleep was a passive action during which the body and brain were fallow. "But it turns out that sleep is a flow during which the encephalon is engaged in a number of activities necessary to life—which are closely linked toquality of life," says Johns Hopkins sleep expert and neurologist Mark Wu, 1000.D., Ph.D. Researchers like Wu are spending many of their waking hours trying to larn more about these processes and how they affect mental and physical health. Hither is a glimpse into the powerful (often surprising) findings of sleep researchers—and what they're still trying to discover about the scientific discipline of sleep.

All Slumber Is Non the Same

Throughout your fourth dimension asleep, your brain will bike repeatedly through 2 different types of slumber: REM (rapid-middle motion) slumber and non-REM sleep.

The first office of the cycle isnot-REM sleep, which is composed of four stages. The first phase comes between being awake and falling asleep. The second is light sleep, when heart rate and breathing regulate and body temperature drops. The 3rd and fourth stages are deep sleep. Though REM sleep was previously believed to be the most of import sleep phase for learning and memory, newer data suggests that non-REM sleep is more than important for these tasks, as well every bit being the more restful and restorative phase of sleep.

Every bit you cycle intoREM sleep, the optics motion rapidly behind closed lids, and encephalon waves are similar to those during wakefulness. Jiff rate increases and the body becomes temporarily paralyzed as we dream.

The cycle then repeats itself, merely with each wheel you spend less fourth dimension in the deeper stages three and iv of slumber and more time in REM slumber. On a typical dark, you'll wheel through four or five times.

Research Shows

An image of a fruit fly's brain, with the sleep-controlling neurons highlighted in green.

Your Genes Touch on Your Slumber Clock

Johns Hopkins sleep skillful and neurologist Marker Wu, Thou.D., Ph.D., and young man researchers recently identified a gene involved in the circadian regulation of sleep timing. When researchers removed this gene—called "wide awake"—from fruit flies, the flies experienced problems falling comatose and staying asleep. A similar sleep gene exists in both humans and mice. Scientists continue to written report this factor in hopes of agreement more about how processes within our cells affect our power to sleep.

Your Torso'due south Built-In Sleep Controls

Co-ordinate to Wu, in that location are two main processes that regulate sleep:cyclic rhythms andsleep drive.

Circadian rhythms are controlled by a biological clock located in the brain. One key part of this clock is responding to light cues, ramping up production of the hormone melatonin at night, then switching it off when information technology senses light. People with total incomprehension ofttimes have problem sleeping considering they are unable to detect and respond to these lite cues.

Sleep drive likewise plays a key part: Your body craves slumber, much like it hungers for nutrient. Throughout the twenty-four hour period, your desire for sleep builds, and when information technology reaches a certain point, y'all need to sleep. A major divergence between sleep and hunger: Your body can't force you lot to swallow when you're hungry, merely when you're tired, information technology can put you to sleep, even if you lot're in a meeting or behind the bike of a machine. When you're wearied, your torso is even able to engage in microsleep episodes of one or ii seconds while your optics are open. Napping for more than than 30 minutes subsequently in the day can throw off your dark's sleep by decreasing your body's sleep drive.

Why Y'all Need Sleep

If you take ever felt foggy afterwards a poor nighttime's sleep, it won't surprise you that slumber significantly impacts brain role. First, a healthy corporeality of sleep is vital for "brain plasticity," or the brain'south ability to suit to input. If nosotros slumber too fiddling, nosotros get unable to process what we've learned during the solar dayand we have more than problem remembering it in the future. Researchers as well believe that slumber may promote the removal of waste products from brain cells—something that seems to occur less efficiently when the brain is awake.

Sleep is vital to the rest of the torso too. When people don't get enough sleep, their health risks ascension. Symptoms of depression, seizures, high blood pressure level and migraines worsen. Immunity is compromised, increasing the likelihood of illness and infection. Slumber too plays a function in metabolism: Even 1 night of missed slumber can create a prediabetic state in an otherwise healthy person. "There are many important connections between health and sleep," says Wu.