10 Things Your Body Does on Autopilot

We like to think we have control over our everyday lives, but in reality we don’t even have control of our bodies — at least not entirely. Yes, we do have many voluntary functions — everything from walking and running to smiling and chewing. These are controlled by your somatic nervous system.

But for every bodily function you do control, there are so many more you don’t. These things — such as breathing and sweating — happen without you ever thinking about them thanks to your autonomic nervous system. This is a good thing, for the most part. Forgetting to stretch in the morning is one thing, but forgetting to breathe would be a much more disastrous oversight. 

You might be able to influence these automatic functions somewhat (you can hold your breath, for instance) but eventually, your body is going to do what it wants, no matter how hard you try to stop it. Here are 10 things your body does automatically that you ultimately can’t override.

Breathing

Breathing is one of the few automatic bodily functions you can briefly control. In fact, controlled breathing is a common method for reducing stress and other benefits. For the most part, though, breathing is controlled by your autonomic nervous system.

Most people can only hold their breath between 30 and 90 seconds, after which your body will say enough is enough and force you to let air in. Your brain constantly monitors carbon dioxide and oxygen levels in your blood and will eventually force you to breathe to keep them at the right amount. 

Obviously, your body is also breathing for you as you sleep. However, sleep apnea may occur when your brain stops sending the proper signals you need to breathe at night.

Digestion

If you’ve ever become nauseous before giving a big speech or felt “butterflies” in your stomach, you’ve experienced how your gut is sensitive to your emotions. That’s because your brain and gastrointestinal (GI) system are closely connected.

But that doesn’t mean you can control how your stomach digests. Your digestive tract runs autonomously, controlled by your enteric nervous system. This regulates everything from releasing the enzymes that break down food to helping your body absorb nutrients.

And while high stress levels can slow your digestion and cause issues such as constipation, you cannot simply turn the digest function of your body off like a light switch. Even dieting, fasting, or suppressing your appetite won’t stop digestion, because your body must absorb nutrients to stay healthy.

Sweating

Sweating is your body’s self-cooling system. It keeps you from overheating on hot days or when you’re exercising. Like other bodily functions, sweating is controlled by your autonomic nervous system. It activates the sweat glands in your skin when your body temperature rises or if something stressful triggers your fight-or-flight response. As perspiration evaporates off your skin, it creates a cooling effect, helping maintain your body temperature around 98.6 degrees Fahrenheit (37 degrees Celsius).

You can try to prevent sweating by applying antiperspirants, wearing breathable clothing, using cooling devices, and even with surgical procedures such as cutting the nerves that trigger perspiration. But not sweating can be dangerous — your body isn’t working hard to maintain your internal temperature just because it feels like. Sweating too little can lead to heat stroke, a potentially life-threatening medical emergency.

Blood Clotting

Every time you get a cut (or an injury to a blood vessel), your body initiates an emergency repair process. Platelets (a type of blood cell) and proteins in your plasma form a clot that plugs the injury to stop the bleeding in a process known as hemostasis. Once your injury heals, the clot should dissolve or break up on its own. 

You can’t prevent any of these processes from happening (and why would you want to?). Some people, however, have a disorder that makes their blood clot too easily. 

These clots can cause unwanted blockages and lead to serious consequences, such as stroke, heart attack, or deep vein thrombosis (DVT). Doctors often prescribe medications such as aspirin or other blood thinners, but even these don’t turn off the hemostasis — they only dampen the body’s blood-clotting ability.

Blushing

You might desperately try to prevent yourself from blushing, especially during awkward social moments, but that usually only makes these moments worse. Blushing is one of the body’s few visible ways to express emotions such as embarrassment, shyness, or stress. It happens when your sympathetic nervous system releases short bursts of blood to the skin in your face, ears, and neck, giving them a reddish hue. 

Because blushing is linked to emotional processing that you also can’t control, it’s nearly impossible to prevent or stop it from happening.

Dilating Pupils

Go ahead, dilate your pupils right now. Obviously, that’s a tall order, because you can’t do so by command. Instead, your pupils — the black centers of your eyes — dilate, or change in size, to adjust how much or how little light is let in. In the dark, they open wide to let as much light in as possible. 

Pupils can also dilate when you experience intense feelings or strong brain activity, such as fear, excitement, and deep concentration.Your pupils are controlled by both your sympathetic and parasympathetic nervous systems. Your sympathetic nervous system, which controls your fight-or-flight response, dilates your pupils,  while your parasympathetic system constricts them as part of a “rest-and-digest” state.

Goose Bumps

You get goose bumps when your sympathetic nervous system causes muscles attached to your hair follicles to contract.

Goose bumps happen for a few different reasons, including to help warm your skin when you’re cold. The change in the surface area of your skin, as well as your pores closing to trap heat, help retain warmth. 

Goose bumps will also occur when you’re going through sudden or intense feelings, whether it’s fear, arousal, or even a response to music or your own thoughts. There’s evidence that some people may be able to trigger their own goose bumps, but science shows that, for most of us, they’re  involuntary.

Shedding Skin Cells

Your skin is constantly replacing itself. According to the Skin Cancer Foundation, you shed 30,000 skin cells every minute to make room for new ones. You can exfoliate or use antiaging products, but you can’t change or stop this cycle. In fact, skin cells grow faster when they’re constantly rubbed or under pressure, but they don’t shed any faster. That’s how calluses form.

Other problems occur when your skin doesn’t shed normally. Two of the most common issues include psoriasis, which speeds up skin cell turnover to just a few days, and ichthyosis vulgaris, which prevents the skin from properly shedding dead cells.

Dreaming

Even while you sleep, your brain is active, creating vivid dreams while it’s processing memories, regulating emotions, and maintaining neurological activity. Dreaming is completely normal, even if it’s an occasional nightmare. Most of us have several dreams every night, even if you don’t remember them. 

And some studies suggest that as many as half of us have had a lucid dream. Lucid dreaming, which occurs during REM sleep, is when you’re aware you’re in your dream. Sometimes, you can even control your actions or what happens. Though the risks seem minimal, researchers say continually trying to have lucid dreams — which some people do — may affect your sleep and even cause health issues.

Cells Dividing

Your body is constantly rebuilding itself through cell division (which is why you can afford to lose all those skin cells). In addition to skin cells, blood cells and cells in your digestive tract are continuously being replaced through mitosis.

During mitosis, a cell duplicates its contents, including its organelles and chromosomes, before splitting into two identical daughter cells. Mitosis is  critical for life, and it’s controlled by your genes — so don’t even think about trying to stop the process. It’s completely automatic, though serious conditions such as cancer can occur when mitosis goes awry.