Learn about which sleep trackers are actually accurate; how important closure is for a life transition; and why mirrors flip horizontally, but not vertically.
Learn about which sleep trackers are actually accurate; how important closure is for a life transition; and why mirrors flip horizontally, but not vertically.
Study of 9 sleep trackers finds that all but 2 are inaccurate by Kelsey Donk
Here's How Important Closure Is for a Life Transition by Sonja Hodgen
Why mirrors flip horizontally but not vertically by Ashley Hamer (Listener question from Maria in Ontario, Canada)
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Find episode transcript here: https://curiosity-daily-4e53644e.simplecast.com/episodes/bad-news-about-your-wearable-sleep-tracker
CODY: Hi! You’re about to get smarter in just a few minutes with Curiosity Daily from curiosity-dot-com. I’m Cody Gough.
ASHLEY: And I’m Ashley Hamer. Today, you’ll learn about which sleep trackers are actually accurate; and how important closure is for a life transition; We’ll also answer a listener question about why mirrors flip horizontally, but not vertically.
CODY: Let’s satisfy some curiosity.
If you want to track how much you sleep, you might try a wearable sleep tracking device. But how precise are those devices, really? That’s what a group of neuroscientists from West Virginia University wanted to find out. And if you use a sleep tracker, the answer may be bad news. Depending on the tracker you use.
For this study, the team tested nine different commercial sleep trackers to see which ones actually worked. And they found that a lot of sleep trackers either over- or under-estimate the number of winks you get per night.
For 98 separate nights, they had five healthy adults sleep while they were hooked up to both commercial sleep trackers and an EEG device. That’s a device that measures the brain’s electrical activity, and it’s a really accurate way to monitor a person’s sleep stages. The researchers looked at total sleep time, total wake time, and sleep efficiency - that’s how long a person slept versus how long they were in bed.
So what did they find? Well, when it comes to how long the participants slept, the best performers were the Fitbit Ionic and the Oura smart ring [OR-uh]. All of the other devices either underestimated or overestimated sleep time, wake time, or sleep efficiency. But none of the commercial sleep devices could accurately detect when participants were experiencing REM or non-REM sleep — even though many devices claim to.
Still, the researchers weren’t that surprised to find that the commercial sleep trackers couldn’t figure out when someone was in deep or light sleep. Tracking REM stages typically requires an EEG, after all.
For many people, the goal of a sleep tracking device is to measure how much sleep they get and how well they sleep. After all, your sleep habits can have an impact on mental health, physical health, and interpersonal relationships.
So there’s a good reason many people use sleep trackers to measure their sleep. But this study shows that your tracker might not be accurate. And that’s bad news, considering that anxiety over how much you’re sleeping can actually make sleep problems worse.
So if you find yourself fretting over what your wearable tells you about your sleep, it might be a good idea to just take it off at night and measure what you can control — what time you go to bed, how much time you spend in bed, and how much wind-down time you give yourself before falling asleep. Just build good habits, and don’t worry about the data.
Let’s say you have a co-worker who’s leaving your company, or a close friend who’s moving out of town. If you’re thinking about throwing a farewell video call, or a socially-distanced happy hour, or some other safe get-together, then I suggest you do it! BECAUSE… it’ll help both of you transition more successfully to the next stage of your lives. And research backs this up: when it comes to life transitions, closure is essential.
Most of the research out there about life transitions has focused on new beginnings, and the kinds of things people need once they’ve started their new life — like, after they've moved into a new home, or started a new job, or embarked on a new relationship. But there hasn’t been as much research on how people deal with endings they see coming, like moving out, or their last day at their old job, or when the clock strikes midnight and their prince has to turn back into a frog. That kind of stuff.
So researchers from NYU decided to do a series of studies. They wanted to find out how the way people end one phase of life influences their transition into a new phase of life.
In some studies, they surveyed college students about their time abroad, or high school students about graduating. The students who described their overall experience and the end of their time as “well-rounded” felt more positive about the experience and better able to cope with what came next. In other studies, researchers had people read stories about people moving from their hometown or leaving a friend’s wedding. People who imagined ending these events in a well-rounded way, like by saying goodbye, felt more positive about the event overall.
There’s even evidence that closure helps you think. In one experiment, the researchers had two strangers have a 10-minute conversation over video chat, just to get to know each other. Some participants were alerted when they had only two minutes left in the conversation so they could end the call in a way that felt well-rounded and complete. Others didn’t receive any warning. Then they all took a test measuring executive function skills — specifically, selective attention and cognitive flexibility. Those who got the two-minute warning that let them wrap up the conversation performed significantly better than those who didn’t get a warning.
Ending the various phases in our lives in a well-rounded way seems to be an important ingredient for lasting happiness. Reason enough to host that fun get-together.
We got a listener question from Maria in Ontario, Canada, who writes, “I love your podcast, and I would love for you to explain why when you look in the mirror, things appear to be flipped horizontally, but not vertically. To extend the question further, how come in a mirror flipped video (over zoom, for example), a right handed person looks left handed, and vice versa. This can get really confusing during my kids’ virtual music lesson!” Great question!
Ok, get ready, because when I first learned about this it blew my mind: mirrors don’t flip anything horizontally. Or vertically. Instead, they flip things front to back. I’ll explain. Say Cody and I are standing face-to-face. I hold up my right hand and Cody holds up his hand on the same side, which is his left. Cody can see my right hand because photons reflect off of it and enter his eyes — photons that hit the right side of my hand from my perspective bounce directly to the left side of Cody’s vision. It’s all a straight shot. But it’s different if I hold up my right hand and look in a mirror. When that happens, photons bounce off my right hand, into the left side of the mirror, from the mirror’s perspective and then back into the right side of my vision. It’s as if Cody had taken a tennis racket and hit those photons back at my right hand.
This might seem like it’s a flip on the horizontal or X axis, but it’s actually a flip on the front-to-back, or Z-axis. Here’s how you know. If you look in a mirror and point right, mirror-you will point right, too. If you point left, it points left. But what happens if you point forward? It doesn’t point forward. It points back. Another way to think about it is to imagine if you were wearing a glove on that pointing hand. If you pull that glove inside out so that your index finger is still touching the same point on the glove, you’d see a hand in the same orientation as your reflection. Your mirror image isn’t you flipped horizontally. It’s you turned inside out.
So why does this happen on video calls? Because you’re seeing a mirror image of yourself and a regular image of the other person, one next to the other. It’s as if I was looking into a mirror with Cody standing next to it facing me. This time, if I raise my right hand, my reflection will show it on my right. But if Cody raises his right hand, I’ll see it on my left. That mirror image can make it look like I’m holding up a different hand than Cody is — in other words, like I’m left handed. One way to fix this? Just turn off “mirror my video” in the Zoom video settings. It might take some getting used to, though, since we’re all most familiar with our own mirror images. Thanks for your question Maria! If you have a question, send it in an email or a voice recording to discovery at curiosity dot com, or leave a voicemail at 312-596-5208.
Leave us a voicemail at 312-596-5208!
CODY: Before we recap what we learned today, here’s a sneak peek at what you’ll hear next week on Curiosity Daily.
ASHLEY: Next week, you’ll learn about a genetic mutation that makes about 20% of people resilient to the cold;
How we could use DNA to preserve human knowledge for thousands of years;
Why the United Kingdom has one of the most memorable postcode systems in the world;
The planetary chaos that happened when the Earth’s magnetic poles reversed;
And more!
CODY: Oh, yeah — and you’ll also hear our interview with Bill Nye. We interviewed Bill Nye. So, you know… stay tuned to hear us talk to Bill Nye.
ASHLEY: [ad lib] But for now, let’s recap what we learned today.
[ad lib optional]
CODY: Today’s stories were written by Kelsey Donk, Sonja Hodgen, and Ashley Hamer, and edited by Ashley Hamer, who’s the managing editor for Curiosity Daily.
ASHLEY: Scriptwriting was by Cody Gough and Sonja Hodgen. Today’s episode was produced and edited by Cody Gough.
CODY: Have a great weekend, and join us again Monday — assuming Ashley is still speaking to me — to learn something new in just a few minutes.
ASHLEY: And until then, stay curious!