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  • If you've heard anything about sleep science,

  • it's probably that you're not supposed

  • to use any screens before bed.

  • And if you're anything like me, you've

  • probably ignored that advice. Because,

  • Come on.

  • Even sleep experts can't resist.

  • Do you use your phone before bed?

  • Yes, just to catch up on my calendar and email,

  • it's always less than 30 minutes for me.

  • That's Rohan Nagare, a sleep researcher

  • who's coauthored several papers on the topic.

  • As a chronic screen's before bed guy myself,

  • I went into our conversation

  • wanting to know if there is any way

  • that we could keep using our phones at night

  • without completely wrecking our sleep schedules.

  • Turns out science suggests

  • our sleep schedule is way more malleable

  • than we might think.

  • Before we dive into the science,

  • let's first get a quick review on how our body responds

  • to natural light like the sun.

  • and the lack thereof.

  • You've probably noticed

  • that at night you naturally start feeling sleepy.

  • This is because your body produces melatonin,

  • a hormone that plays a huge role in sleep.

  • melatonin is not just, any other hormone.

  • it's kind of an internal timekeeper.

  • As the sun rises

  • and you get exposed to its bright light, your body suppresses

  • the production of melatonin, helping you feel awake and alert.

  • But sun exposure isn't the only factor here.

  • The color temperature of light also changes throughout the day.

  • Daylight exists at roughly 5600 Kelvin, which leans quite blue.

  • A sunset leans much warmer in the 3000 Kelvin range.

  • This natural color

  • shift, combined with the decreasing brightness,

  • tells our body to kick

  • start the production of melatonin, which makes us feel sleepy.

  • Natural light makes things simple on our bodies.

  • But once you start adding artificial light into the mix,

  • things get a little more complicated.

  • Especially when we're staring at these all night.

  • Phone screens at their baseline

  • have a color temperature of 5600 Kelvin, or daylight.

  • So when you hear that

  • using your phone before bed is bad for you.

  • This is the commonly cited reason as to why.

  • The phone's artificial daylight, aka

  • blue light, suppresses the production of melatonin,

  • disrupting our feelings of sleepiness.

  • Now, You might be wondering, don't phones

  • have a built in feature

  • that's intended to counteract this blue light?

  • They do.

  • It's called night mode or night shift.

  • But does it actually work?

  • Well, In 2019, Rohan

  • coauthored a study that tried to answer that question.

  • It's a very smart feature,

  • The idea is right, they're trying to manipulate

  • a lighting characteristic, which is the spectrum,

  • to reduce the circadian effectiveness.

  • The study looked at two modes of warm shift

  • high CCT which meant that the screen

  • colors were intensely shifted to the warmer end of the spectrum

  • and low CCT

  • which meant that there was only a slight warm shift.

  • Both modes suppressed

  • melatonin, the sleepy hormone, and the results showed

  • that there wasn't a meaningful difference between the two.

  • And while that makes it sound like Night Shift doesn't work,

  • it's actually a lot more complicated than that.

  • Spectrum is just one aspect.

  • Distribution duration, timing and amount needs to be considered

  • So if you're using phone in the night,

  • I wouldn't be too concerned if it's 20 minutes, 30 minutes.

  • But if it's beyond that,

  • if you're going to watch a movie every night

  • or like three episodes of a Netflix show,

  • you know, then it accumulates a pretty good circadian dose,

  • which can keep delaying you every day.

  • What Rohan is saying here

  • is that limiting the time you spend on

  • your phone can also make a difference,

  • and warm shift is just part of the solution.

  • When we use our phones

  • were staring directly into a light source

  • and how much light falls onto a certain area

  • like our eyes, usually measured.

  • in lux is dramatically impacted by our closeness to the device.

  • In fact, you experience a closer light source as four times

  • more powerful than that

  • same light source twice the distance away from you.

  • if you're going to get 1000 lux at your eye,

  • it honestly doesn't matter

  • if it's a warm source

  • or a cool source, that's too high and you're already

  • saturating your circadian system.

  • So we know that limiting screen duration,

  • shifting the colors warmer,

  • and lowering the brightness all helps.

  • But Rohan also let me in on an interesting biological hack

  • that can make a huge difference

  • in how impactful your late night screen time is.

  • what you really want is a contrast

  • between how much light you get immediately after you wake up

  • for an hour or two, and immediately

  • before you sleep 1 or 2 hours.

  • It's possible to trick your circadian system and say, okay,

  • if I'm going to blast my screen brightness

  • and bump up my 50 lux to 200 lux in the evening,

  • I can just counter that

  • by getting 800 lux in the morning.

  • So that's the beauty of your circadian system.

  • You can use its own mechanisms against it.

  • So basically, if you go for a sunny walk in the morning,

  • you could potentially offset the amount of circadian disruption

  • you're experiencing from your phone.

  • At the end of the day.

  • Body hacks aside,

  • the thing that I realized as I was researching

  • this story is that

  • there are so many more factors that impact our sleep

  • besides just the blue light that comes out of our phones.

  • And we haven't even touched on them all yet.

  • Like what you do on your phone,

  • whether it be doom-scrolling or watching a scary movie,

  • all that can be just as stimulating

  • and disruptive to your sleep

  • as the amount of light that you're taking in.

  • At the end of the day, figuring out

  • how to have a healthier relationship with our devices

  • is a big step

  • in figuring out how to have a healthy

  • relationship with our sleep.

  • Thank you so much for watching this episode of Even Better.

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If you've heard anything about sleep science,

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