Sleep researchers divide sleep into four stages, stages 1, 2, 3 and REM, but for simplicity we group them into the following three stages: light, deep and REM. Here's what each one means.
Stage 1: "This is the sleep that's a little bit more choppy, superficial, not restful," says Michael Grandner, MD, director of the Sleep and Health Research Program at the University of Arizona in Tucson. "But it's usually just a quick transition, so you're not in it for very long.
During stage one, "you still hear things and you have a sense of awareness," says Allison Siebern, PhD, consulting assistant professor at The Stanford Center for Sleep Sciences and Medicine and director of the Sleep Health Integrative Program at Veterans Affairs Medical. Center in Fayetteville, NC. "Your brain is dozing off, but you don't feel you're asleep."
Stage 2: When people talk about light sleep, this is the stage they usually refer to. You sleep, but can be easily awakened. That said, stage 2 sleep is not superficial, nor is it less important than other sleep stages. "Light sleep is very important because it takes up more than half of the night," says Grandner. "It's when your body processes memories and emotions and your metabolism regulates itself. So a lot of body maintenance takes place during the lighter stages of sleep." Breathing and heart rate usually decrease slightly during this phase.
Stage 3: During deep sleep you are less sensitive to external stimuli. Breathing slows down and muscles relax; the heartbeat usually becomes more regular.
“Deep sleep is mostly about the body,” says Grandner. "The thinking parts of the brain are mostly offline. Your muscles are very relaxed. You don't dream at all during this period. Your body does a lot of rebuilding and repair." Deep sleep is when your body secretes growth hormone, which is associated with cellular rebuilding and repair. According to Siebern, deep sleep has also been shown to strengthen your immune system.
"If deep sleep is about the body, REM is about the brain," says Grandner. "The brain is very active during REM sleep, but the body is inactive. In fact, it's so inactive that you're actively paralyzed during REM sleep."
REM is the moment when you dream the most and your eyes move quickly (hence the name: Rapid Eye Movement). The heart rate increases and your breathing becomes more irregular.
REM is very important for emotion regulation and memory - your brain clears itself of unnecessary things, says Siebern. It is also the peak of protein synthesis at the cellular level, which keeps many processes in the body working properly.
UNDERSTANDING SLEEP CYCLES
Your body does not go through each sleep stage once a night, nor does it spend the same amount of time in each stage. In fact, it goes through all of these stages several times a night. “Each cycle lasts an average of 90 minutes,” says Grandner, “but some cycles can be as short as 50 minutes and some can be as long as 100 minutes or more.” According to Grandner, it works like this:
Cycle 1: During light sleep, you start in phase one and move on to phase two. Then you quickly transition into deep sleep, which you stay in for a while before moving into about 10 minutes of REM sleep. "It's very hard to wake up from a deep sleep, so your body tries to get over it as quickly as possible," says Grandner. "By the time the night is halfway through, you're usually done with it."
Cycle 2: You get a little more light sleep, still a lot of deep sleep (but less than before), and a little more REM.
Cycle 3: You will probably spend a lot more time in light sleep, a little deep sleep, and more REM.
After this, during the second half of the night, the cycles usually break down as your body alternates between light sleep and REM for the rest of the night.
On average, light sleep takes up about 50 to 60 percent or more of the night. "Whether you get more or less light sleep doesn't really affect how you feel much, because it's just the time left that isn't spent in deep sleep or REM," says Grandner. "It's kind of leftover."
Deep sleep, on the other hand, probably takes up 10 to 25 percent (depending on your age) of your sleep. "There's no real way to get too much deep sleep," says Grandner. "Your body has its own natural urge for it, so once you satisfy that, the need goes away and you just go into REM and light sleep."
Too little, on the other hand, will make you wake up less rested. "The two main things that can lead to less deep sleep are age and anything that interferes with your sleep, such as pain, illnesses, medical problems, sleep apnea, and other sleep disorders," says Grandner. "They can artificially keep you out of deep sleep, making your sleep a bit more superficial." Also exchange services. "Your body wants to get into deep sleep at night, and during the day it wants to avoid deep sleep," says Grandner. "So you have a natural lag of how long it takes you to get into it."
Finally, REM makes up about 20 to 25 percent of your nightly sleep and usually takes place in the second half of the night. "When you shorten your sleep, most of what you cut out is REM," says Grandner. "And too little REM sleep can make you feel drowsy, less able to concentrate, and lead to memory problems." That's why it's important to get enough rest after learning something new or before taking an exam. Many drugs can also block REM. "Most antidepressants can cut REM sleep in half," says Grandner.
Consistently getting too much REM can also cause problems. “Going too much above 25 percent REM can lead to too much brain activation, which can make you angry and irritable and even worsen depression and anxiety symptoms,” says Grandner.
"Everyone is different," says Grandner. "As long as you give yourself enough time to sleep, and you don't have a sleep disorder that keeps you out of certain stages of sleep, your body will figure it out on its own using its own rhythms and drivers."
Siebern agrees: "We can do things to help improve the quality of our sleep, but we all have a baseline that dictates how much of each sleep stage we get." (Check out these 8 tips for a good night's sleep.) There isn't really an ideal.
"Ideal is what your body does when given enough opportunity," says Grandner. Ask yourself, suggests Siebern, how you feel. If your sleep stages are outside the average, but you feel fresh and active, you're probably getting the amount and quality of sleep you need. Our customers often tell us that they already felt fit, but are now aware that there was still a lot to gain. Or have a good night's sleep while they slept less. In short, our supplement ensures that your sleep quality is increased. So you can book a good night's sleep in less time.
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