Most of us don’t know what’s happening to our bodies while we’re sleeping, because we are asleep! Sleep evokes images of closed eyes, slow breathing, dreams and relaxation. But while you're dozing, your body's systems are doing lots of crazy things that will blow your mind.
Some of these crazy mind blowing things are listed below:
1. Your body temperature drops.
Just before you fall asleep, your core body temperature begins to decrease. This drop signals to your brain to release melatonin, which affects your circadian rhythm (or sleep/wake cycle) and tells your body it's time for bed. Your temperature is lowest around 2:30 A.M., so if you're able to, program your thermostat to rise one degree at that time for an hour or two. Otherwise, you may find yourself stealing your spouse’s covers for extra warmth.
2. You lose weight.
One reason you should always step on a scale in the morning, not in the evening is that you lose water through perspiring and breathing out humid air during the night. This happens during the day too, but eating and drinking while you're awake negates any weight loss. If you're sleeping just four or five hours per night, you could be canceling out whatever smart diet and exercise choices you're making during the day. To whittle your waistline, get at least seven hours of sleep per night.
3. You get taller.
You do gain height while you sleep. The discs in your spine that act as cushions between the bones rehydrate and get bigger because the weight of your body isn't pressing down on them, like it is when you're standing. If you have a firm mattress, sleeping on your side in the fetal position may be best for getting taller because it decreases the load on your back.
Your body produces a hormone known as the human growth hormone (hgH) while you are in the deepest stages of sleep. This hormone is necessary for the growth of your muscles, bones and tissues when you are young, and then for repair and restoration once you stop growing. It is also the reason for the term ‘beauty sleep’ – sleep considered to be sufficient to keep one looking young and beautiful.
4. Your blood pressure and heart rate decrease.
When you're resting, your body doesn't need to work as hard or pump as much blood, so these systems slow down. Blood pressure needs to dip at night so your cardiac muscle and circulatory system have time to relax and repair.
It's especially important for people with high blood pressure to get at least seven hours of sleep to experience that temporary drop—it reduces the risk for heart disease.
5. Your muscles are temporarily paralyzed.
Sounds scary, but it's actually what keeps you from acting out your dreams.
That "can't...move...another...muscle" feeling comes from the fact that all sorts of normal physiological processes slow way down at bedtime, like how many breaths you take per minute and how quickly your heart beats. Even your muscles and organs chill out. The intestines quiet down in the nighttime, and the liver goes from trying to detoxify during wakefulness to trying to build and synthesize when you're sleeping. There's also less adrenaline pumping through your veins, since you won't be needing your fight-or-flight response between the sheets.
When you sleep, your throat muscles relax, causing your throat to get narrower and your breathing to change. Some people’s throats get too narrow though, which is why they tend to snore.
6. Your eyes twitch.
During REM (aka rapid eye movement) sleep, your eyes dart from side to side, not that scientists know why exactly. Dreams occur during REM sleep, so it can be disconcerting to wake up during this deep—not light—sleep stage. You might feel most refreshed if you wake up right after you cycle through all the sleep stages, with REM occurring toward the end. Though it varies from person to person, one sleep cycle usually lasts 90 minutes, so try sleeping in intervals of 90 minutes. For example, you may find it easier to awaken after sleeping for 7.5 hours (five cycles) than after 8 hours (5⅓ cycles).
7. You get sexually aroused.
Just as men get erections during REM sleep, women become sexually stimulated then, too. Your brain is more active during REM sleep (since you're dreaming), so it requires more oxygen—as a result, blood flow all over the body increases. There is natural clitoral engorgement because blood rushes to that area and causes swelling, according to research.
8. You're more likely to have gas.
You won't be happy to hear this, but during the night, your anal sphincter muscles loosen slightly, making it easier to let out a toot or two. Luckily, your sense of smell (and your spouse's) are reduced while you sleep—that's why fire alarms were invented, because it's hard to smell smoke while you're snoozing. So even if you experience flatulence, rest assured: Nobody is likely to notice.
9. You may have a full-body spasm.
As people fall asleep, many of them experience a full-body jerk, and it's totally normal. As many as 70% of people experience this phenomenon in which muscles suddenly contract. Some experts think that these spasms may have to do with anxiety and/or an irregular sleep schedule, while others think they're unavoidable. So if you like to snuggle with your spouse as you wind down in bed, be sure to pry yourselves apart before you're both out cold, or else you may accidentally shake each other awake.
10. Collagen production in your skin increases.
Collagen is a protein that strengthens blood vessels and gives skin its elasticity. When you're asleep, you're in a fasting state, so growth hormone is released to tell your fat cells to release energy stores—as it turns out, growth hormone also stimulates collagen growth. "Since collagen production spikes while you sleep, moisturizing facial creams that contain retinols and retinoids are best to use before bed because these products boost collagen turnover, combat pigment problems and fight fine lines and wrinkles," says Melanie Palm, MD, a dermatologist in Solana Beach, CA, an assistant clinical professor at the University of California, San Diego, and a staff physician at Scripps Encinitas Memorial Hospital.
11. You aren't sleeping deeply most of the time.
Not all sleep was created equal: When you first drift off, you get only very light sleep, then progress deeper and deeper into dreamland. The sleep cycle starts in what's called non–rapid eye movement or NREM stage 1 (the kind of sleep you might nab if you were the type to doze off during your college lectures). Then you move into a deeper NREM 2 and then to the deepest, NREM 3, also called slow-wave sleep. Finally, you land in rapid eye movement, or REM, sleep, the wild part of the ride when most of our dreams occur. The whole cycle usually takes somewhere between 90 and 120 minutes, so on a typical night you'll cycle through four or five times, waking up for just a sec (even if you don't realize you're awake) after REM sleep before starting over in stage 1.
As the night goes on, you spend less time in that deliciously deep stage 3 and more time in REM sleep, which explains why your alarm so often wakes you up in the middle of a totally bizarre dream. REM sleep may somehow prepare you to get your butt out of bed.
12. Your brain cleans house.
Our brains are "on" throughout the night, especially in that dream-heavy REM sleep when they're actually almost as active as they are when we're wide awake.
Among other things, they may be taking out the trash. That's one of the more exciting new ideas about the purpose of sleep: A 2013 study in mice found that waste removal systems in the brain are more active during sleep.
Your brain's also busy cementing new memories while you sleep. The brain is processing the information we gained throughout the day and filtering out the information we don't need, which may be one of the reasons we dream. The theory goes that maybe connections between brain cells are strengthened or weakened during sleep, depending on how much we used them during the day. The important stuff gets reinforced while the factoids we just don't need get trashed.
13. Sleep regulates your hunger hormones
If a frosted donut has ever looked particularly tasty after a night spent tossing and turning, at least it's not just you: Most people reach for higher-calorie foods (and more of 'em) when they've logged too few hours of sleep, which can in turn, of course, lead to weight gain. Researchers believe that the hunger-regulating hormones leptin and ghrelin get out of whack when we don't sleep well.
14. You might walk, talk, or even drive.
There's no good reason for these so-called parasomnias, or weird behaviors known to happen during sleep, but luckily they're mostly harmless. Sleepwalking and similar midslumber activities occur during stage 3 sleep, making it tough to rouse a sleepwalker from deep sleep but not dangerous to do so. (In fact, it can be dangerous not to wake them, considering their next move could be to try to get behind the wheel.) Sleepwalking, talking, or driving is usually due to sleep deprivation or is a side effect of certain medications and occurs in anywhere from 1 to 15% of us, according to the National Sleep Foundation. While it's definitely most common in kids, you probably don't have to worry if you find your spouse has migrated to the living room.
15. Dream
Some people cannot remember their dreams in the morning, while others wake up remembering a bizarre sequence of events that often seem real. Many dreams are based in reality, with elements of the person’s thoughts or the events of the previous day featuring prominently in what they dream about. Psychologists have offered several theories to explain why we dream, but so far there is no consensus. Some people even have recurring dreams, where they experience they same dream either in a short period of time or over several years.
16. You May Grind Your Teeth
Many people grind their teeth together or clench them while they are asleep, a condition that is known as bruxism. If you suspect that you may be grinding your teeth at night, you should go to your dentist and get fitted for a mouth guard immediately, because the habit could leave you with cracked teeth and sore jaw muscles.
Click here to see a video of some weird things we do during sleep
