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How Does Blood Pressure Work?

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Your heart is the master pump for all the blood in your body. With every heartbeat, your heart pushes your blood to all the vital parts of your body, such as muscles and bones, through a network of arteries, capillaries, and veins. As blood flows through the tube-like arteries, it presses up against the walls of the blood vessels with varying degrees of strength. The strength or weakness of this pressure is called your blood pressure (BP).

Each time your heart squeezes, moving your blood to its various destinations, your blood pressure goes up—this number is referred to by a blood pressure reading as systolic. Then, as the heart relaxes after each contraction, your blood pressure goes down; that is called the diastolic reading. Together, these two numbers are presented as a score, systolic over diastolic: Your doctor might tell you that your BP is “120 over 80.”

According to the American Heart Association (AHA), normal blood pressure should reflect systolic pressure between 90 and 120, over a diastolic pressure between 60 and 80. Your doctor may take this measurement with a fancy-named instrument called a sphygmomanometer—an inflatable rubber cuff attached to a manual air pump. When the doctor inflates the cuff at your arm with air, it temporarily cuts off blood flow, and when it releases, the blood starts flowing again, revealing those two key numbers.

Nowadays, though, doctors are recommended to use an automatic blood pressure cuff, which relies on a different method and seems to be more accurate. While the manual cuff relies on auscultation, in which the doctor listens for the correct pressures using a stethoscope/microphone, automatic blood pressure cuffs are usually oscillometric. When blood passes under the cuff, the arm increases in circumference ever so slightly. And by measuring the amplitude of the oscillations (hence oscillometric) at a continuous interval of pressures, blood pressure can be calculated in much the same way.

If you have high blood pressure, a.k.a. hypertension—approximately 130/80 or higher in a person of average health—your heart is working too hard to pump the blood through your body, which becomes dangerous. According to the AHA [PDF], elevated blood pressure is 120–129/less than 80; hypertension stage 1 is 130–139 (systolic) or 80–89 (diastolic); and hypertension stage 2 is 140 or higher (systolic) or 90 or higher (diastolic). If your blood pressure hits 180/120, you're in hypertensive crisis, and you should get help.

If you fall into the above categories, your doctor will recommend changes to diet and exercise and probably medication. High blood pressure is often a precursor to heart disease or a heart attack and can be a side effect of other diseases, such as diabetes. However, your blood pressure can temporarily rise due to stress, pregnancy, and even some common medications, including over-the-counter pain relievers and antidepressants. One high reading will not necessarily mean you have hypertension—but it’s good to keep vigilant.

Editor's note: This story was updated in July 2018 to reflect new blood pressure guidelines from the AHA.

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6 Signs You're Getting Hangry
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Hangry (adjective): Bad-tempered or irritable as a result of hunger. This portmanteau (of hungry and angry) is not only officially recognized as a word by the Oxford English Dictionary, but it's also recognized by health experts as a real physiological state with mood-altering consequences.

That hangry feeling results from your body's glucose level dropping, putting you into a state of hypoglycemia, or low blood sugar. Glucose is the body's primary source of energy, so when you don't have enough, it affects your brain and other bodily functions, including the production of the hormones insulin and glucagon, which help regulate blood sugar. Check out the symptoms below to see if you've crossed over into the hanger danger zone.

1. IT TAKES EVERYTHING IN YOUR POWER JUST TO KEEP YOUR EYES OPEN.

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Glucose equals energy, so when your blood sugar levels are low, you may start wishing you were back in bed with the shades drawn. If you start feeling sluggish or tired even though you’re well-rested, you might just need to eat something.

2. THE EASIEST ITEM ON YOUR TO-DO LIST SEEMS LIKE AN IMPOSSIBLE TASK …

It’s hard to concentrate when all you can think about is whether you're going to order the fish or beef tacos for lunch. The distraction goes beyond fantasies about food, though. The brain derives most of its energy from glucose, so when it's low on fuel, a serious case of brain fog can set in. Confusion and difficulty speaking are among the more serious symptoms you may experience when you're hangry.

3. … AND YOU HAVE A BAD CASE OF WORD VOMIT.

Blame this on brain fog too. The gray matter in your noggin goes a little haywire when blood sugar is in short supply. That's why you may start stuttering or slurring your words. You might also have difficulty finding your words at all—it can feel like your mouth and brain are disconnected.

4. YOU’RE SHAKING LIKE A LEAF AND FEEL LIGHTHEADED.

Tremors and dizziness are both signs that you should pay closer attention to your body, which is screaming, "Feed me!" Once again, low blood sugar is often the culprit of trembling hands and feeling faint, and exhaustion and stress make the symptoms worse.

5. YOUR COWORKERS SEEM ESPECIALLY ANNOYING.

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You’re tense and irritable, and it’s starting to show. Hunger causes your body to release cortisol and adrenaline, the same hormones responsible for stress. This can put you on edge and lower your tolerance for other people’s quirks and irksome habits, which suddenly seem a lot less bearable.

6. YOU SNAPPED AT YOUR FRIEND OR PARTNER FOR NO GOOD REASON.

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Not only are you irritable, but you’re more likely to lash out at others because of it. The doses of adrenaline and cortisol in your body can induce a fight-or-flight response and make you go on the attack over matters that—if you had some food in you—would seem unimportant.

So what should you do if these descriptions sound all too familiar? Eat a snack, pronto—one with complex carbohydrates, lean protein, and healthy fats. The first one brings up your blood sugar level, and the other two slow down how fast the carbohydrates are absorbed, helping you to avoid a sugar crash and maintain a normal blood sugar level. Eating small meals every few hours also helps to keep hanger at bay.

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Casper
You Can Now Book a Nap Nook in New York City
Casper
Casper

New York might be the city that never sleeps, but its residents need to catch some Zs every now and then—even at times when it's least convenient. As spotted by Dezeen, mattress maker Casper has come up with a clever solution for those moments when you simply can't keep your eyes open at work: rentable nap pods.

At The Dreamery, the company's mattress-filled downtown Manhattan facility, snooze sessions in your own private nook can be booked on Casper's website or on a walk-in basis. The $25 fee will get you a pair of constellation-print pajamas, 45 minutes of downtime in a circular sleep pod, refreshments, and skin care products.

One of the common concerns is hygiene, and it's something that Casper has addressed in its FAQ section. According to the company, all of the bedding is stripped and laundered in between nap sessions, "and constant airflow will keep the space feeling and smelling fresher than a hotel room."

Each pod is outfitted with auto-fading lights, a reading light, a sound-absorbing back wall, and a bedside shelf with outlets. Casper also collaborated with Headspace, a company specializing in daily mindfulness exercises, to provide a selection of "sleepcasts" that take listeners on guided meditations of a deep sea submarine expedition or a walk through a surreal landscape.

The lights gradually turn back on at the end of the session, and patrons can freshen up in The Dreamery's lounge with a cup of coffee before heading back to the office or out for a day of sightseeing.

"The Dreamery is about making sleep and rest a part of our regular wellness routines—similar to how many people prioritize a workout class," Neil Parikh, Casper's co-founder and COO, said in a statement.

Located at 196 Mercer Street in SoHo, The Dreamery is ideal for employees in Lower Manhattan who could use a quick catnap between meetings or for visitors who have a jam-packed tourist itinerary, and it stays open fairly late—up to 8 p.m. Monday through Saturday, and 6 p.m. on Sundays.

[h/t Dezeen]

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