CLOSE
Original image
iStock

Does Evolution Explain Why Our Sleep Habits Change With Age?

Original image
iStock

Laugh all you want now about Grandma's 8 p.m. bedtime; after reading this, you might just want to thank her. One team of researchers report that older adults' earlier body clocks may have evolved to ensure that at least one person was always awake to watch over a family group. They published their findings in the Proceedings of the Royal Society B.

Scientists believe that many groups of social animals take turns sleeping and standing guard. This sentinel hypothesis, as it's known, is easiest to observe in a line of sleeping ducks; the last duck in a row literally sleeps with one eye open. But we didn't know whether this phenomenon extended to humans.

To find out, researchers collaborated with Hadza people of northwestern Tanzania. Many Hadza maintain a hunter-gatherer lifestyle, working and sleeping far from the noise and light pollution of the cities. The researchers recruited a group of 33 adults between the ages of 20 and 60 and gave each person an actigraphic (movement-tracking) wristband. For 20 nights, the actigraphs recorded participants' tossing and turning, their waking, and their stillness in sleep.

The big-picture results looked a lot like you might expect. Average bed- and wake-up times were around 10 p.m. and 7 a.m., respectively. But those were just the averages. Within even this small group, two familiar chronotypes emerged: the older early birds, who bedded down around 8 p.m. and woke by 6 a.m., and the younger night owls, who were up past 11 p.m. and slept until 8 a.m.

Most compellingly, the researchers say, nobody ever slept through the night. Each person woke several times per sleep period, whether to pee, go for a smoke, soothe a crying baby, or just roll over in bed. The resulting gaps in sleep time meant that someone in the group was awake at almost all times. Out of 20 nights, there were only 18 minutes in which the entire group was sound asleep.

Co-author Charlie Nunn is an evolutionary anthropologist at Duke University. He says the group's early bird/night owl split, combined with the frequent mid-sleep awakenings, may be our bodies' way of keeping our families safe.

"If you're in a lighter stage of sleep, you'd be more attuned to any kind of threat in the environment," he said in a statement.

Nunn and his colleagues suggest that the staggered sleeping shifts are not an accident but an adaptation.

"A lot of older people go to doctors complaining that they wake up early and can't get back to sleep," Nunn said. "But maybe there's nothing wrong with them. Maybe some of the medical issues we have today could be explained not as disorders, but as a relic of an evolutionary past in which they were beneficial.”

Maybe. Maybe not. It's quite possible that older adults' sleep issues are just that: issues, and signs of an aging body. We'll need a lot more research on the subject before we can say for sure. In the meantime, let's cut Grandma some slack. Evolutionary advantage or no, we all just want to sleep.

Original image
AFP/Stringer/Getty Images
arrow
Space
SpaceX's Landing Blooper Reel Shows That Even Rocket Scientists Make Mistakes
Original image
SpaceX's Falcon 9 rocket launches.
AFP/Stringer/Getty Images

On March 30, 2017, SpaceX did something no space program had done before: They relaunched an orbital class rocket from Earth that had successfully achieved lift-off just a year earlier. It wasn't the first time Elon Musk's company broke new ground: In December 2015, it nailed the landing on a reusable rocket—the first time that had been done—and five months later landed a rocket on a droneship in the middle of the ocean, which was also unprecedented. These feats marked significant moments in the history of space travel, but they were just a few of the steps in the long, messy journey to achieve them. In SpaceX's new blooper reel, spotted by Ars Technica, you can see just some of the many failures the company has had along the way.

The video demonstrates that failure is an important part of the scientific process. Of course when the science you're working in deals with launching and landing rockets, failure can be a lot more dramatic than it is in a lab. SpaceX has filmed their rockets blowing up in the air, disintegrating in the ocean, and smashing against landing pads, often because of something small like a radar glitch or lack of propellant.

While explosions—or "rapid unscheduled disassemblies," as the video calls them—are never ideal, some are preferable to others. The Falcon 9 explosion that shook buildings for miles last year, for instance, ended up destroying the $200 million Facebook satellite onboard. But even costly hiccups such as that one are important to future successes. As Musk once said, "If things are not failing, you are not innovating enough."

You can watch the fiery compilation below.

[h/t Ars Technica]

Original image
iStock
arrow
Health
8 Potential Signs of a Panic Attack
Original image
iStock

It's not just fear or worry. In fact, many panic attacks don’t look like panic at all. Panic attacks come on rapidly, and often at times that don't seem to make sense. The symptoms of panic disorder vary from person to person and even from attack to attack for the same person. The problems listed below are not unique to panic attacks, but if you're experiencing more than one, it's a good idea to talk to your doctor either way.

1. YOU'RE DIZZY.

Doctors sometimes call the autonomic nervous system (ANS) the "automatic nervous system" because it regulates many vital bodily functions like pumping blood all on its own, without our having to think about it. Panic attacks often manifest through the ANS, leading to increased heart rate or decreased blood pressure, which can in turn lead to feeling lightheaded or faint.

2. YOU'RE LOSING YOURSELF.

Feeling detached from yourself is called depersonalization. Feeling detached from the world, or like it's fake or somehow unreal, is called derealization. Both forms of dissociation are unsettling but common signs that a panic attack has begun.

3. YOU'RE QUEASY.

Our digestive system is often the first body part to realize that something is wrong. Panic sends stress hormones and tension to the gut and disrupts digestion, causing nausea, upset stomach, or heartburn.

4. YOU FEEL NUMB OR TINGLY.

Panic attacks can manifest in truly surprising ways, including pins and needles or numbness in a person's hands or face.

5. YOU'RE SWEATY OR SHIVERING.

The symptoms of a panic attack can look a lot like the flu. But if you don't have a fever and no one else has chattering teeth, it might be your ANS in distress.

6. YOU KNOW THE WORST IS COMING.

While it may sound prophetic or at least bizarre, a sense of impending doom is a very common symptom of panic attacks (and several other conditions). 

7. BREATHING IS DIFFICULT.

The ANS strikes again. In addition to the well-known problems of hyperventilation or shortness of breath, panic attacks can also cause dyspnea, in which a person feels like they can't fill their lungs, and feelings of choking or being smothered.

8. YOU'RE AFRAID OF HAVING A PANIC ATTACK. 

Oddly enough, anxiety about anxiety is itself a symptom of anxiety and panic attacks. Fear of losing control or getting upset can cause people to avoid situations that could be triggering, which can in turn limit their lives. 

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios