How much does your phone’s blue light really delay your sleep? Relax, it’s just 2.7 minutes
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It’s one of the most pervasive messages about technology and sleep. We’re told bright, blue light from screens prevents us falling asleep easily. We’re told to avoid scrolling on our phones before bedtime or while in bed. We’re sold glasses to help filter out blue light. We put our phones on “night mode” to minimise exposure to blue light.
But what does the science actually tell us about the impact of bright, blue light and sleep? When our group of sleep experts from Sweden, Australia and Israel compared scientific studies that directly tested this, we found the overall impact was close to meaningless. Sleep was disrupted, on average, by less than three minutes.
We showed the message that blue light from screens stops you from falling asleep is essentially a myth, albeit a very convincing one.
Instead, we found a more nuanced picture about technology and sleep.
What we did
We gathered evidence from 73 independent studies with a total of 113,370 participants of all ages examining various factors that connect technology use and sleep.
We did indeed find a link between technology use and sleep, but not necessarily what you’d think.
We found that sometimes technology use can lead to poor sleep and sometimes poor sleep can lead to more technology use. In other words, the relationship between technology and sleep is complex and can go both ways.
How is technology supposed to harm sleep?
Technology is proposed to harm our sleep in a number of ways. But here’s what we found when we looked at the evidence:
- bright screen light – across 11 experimental studies, people who used a bright screen emitting blue light before bedtime fell asleep an average of only 2.7 minutes later. In some studies, people slept better after using a bright screen. When we were invited to write about this evidence further, we showed there is still no meaningful impact of bright screen light on other sleep characteristics including the total amount or quality of sleep
- arousal is a measure of whether people become more alert depending on what they’re doing on their device. Across seven studies, people who engaged in more alerting or “exciting” content (for example, video games) lost an average of only about 3.5 minutes of sleep compared to those who engaged in something less exciting (for example, TV). This tells us the content of technology alone doesn’t affect sleep as much as we think
- we found sleep disruption at night (for example, being awoken by text messages) and sleep displacement (using technology past the time that we could be sleeping) can lead to sleep loss. So while technology use was linked to less sleep in these instances, this was unrelated to being exposed to bright, blue light from screens before bedtime.
Which factors encourage more technology use?
Research we reviewed suggests people tend to use more technology at bedtime for two main reasons:
- to “fill the time” when they’re not yet sleepy. This is common for teenagers, who have a biological shift in their sleep patterns that leads to later sleep times, independent of technology use.
- to calm down negative emotions and thoughts at bedtime, for apparent stress reduction and to provide comfort.
There are also a few things that might make people more vulnerable to using technology late into the night and losing sleep.
We found people who are risk-takers or who lose track of time easily may turn off devices later and sacrifice sleep. Fear of missing out and social pressures can also encourage young people in particular to stay up later on technology.
What helps us use technology sensibly?
Last of all, we looked at protective factors, ones that can help people use technology more sensibly before bed.
The two main things we found that helped were self-control, which helps resist the short-term rewards of clicking and scrolling, and having a parent or loved one to help set bedtimes.
Why do we blame blue light?
The blue light theory involves melatonin, a hormone that regulates sleep. During the day, we are exposed to bright, natural light that contains a high amount of blue light. This bright, blue light activates certain cells at the back of our eyes, which send signals to our brain that it’s time to be alert. But as light decreases at night, our brain starts to produce melatonin, making us feel sleepy.
It’s logical to think that artificial light from devices could interfere with the production of melatonin and so affect our sleep. But studies show it would require light levels of about 1,000-2,000 lux (a measure of the intensity of light) to have a significant impact.
Device screens emit only about 80-100 lux. At the other end of the scale, natural sunlight on a sunny day provides about 100,000 lux.
What’s the take-home message?
We know that bright light does affect sleep and alertness. However our research indicates the light from devices such as smartphones and laptops is nowhere near bright or blue enough to disrupt sleep.
There are many factors that can affect sleep, and bright, blue screen light likely isn’t one of them.
The take-home message is to understand your own sleep needs and how technology affects you. Maybe reading an e-book or scrolling on socials is fine for you, or maybe you’re too often putting the phone down way too late. Listen to your body and when you feel sleepy, turn off your device.
Chelsea Reynolds, Casual Academic/Clinical Educator and Clinical Psychologist, College of Education, Psychology and Social Work, Flinders University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Pinch Of Nom, Everyday Light – by Kay Featherstone and Kate Allinson
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One of the biggest problems with “light”, “lean” or “under this many calories” cookbooks tends to be the portion sizes perhaps had sparrows in mind. Not so, here!
Nor do they go for the other usual trick, which is giving us something that’s clearly not a complete meal. All of these recipes are for complete meals, or else come with a suggestion of a simple accompaniment that will still keep the dish under 400kcal.
The recipes are packed with vegetables and protein, perfect for keeping lean while also making sure you’re full until the next meal.
Best of all, they are indeed rich and tasty meals—there’s only so many times one wants salmon with salad, after all. There are healthy-edition junk food options, too! Sausage and egg muffins, fish and chips, pizza-loaded fries, sloppy dogs, firecracker prawns, and more!
Most of the meals are quite quick and easy to make, and use common ingredients.
Nearly half are vegetarian, and gluten-free options involve only direct simple GF substitutions. Similarly, turning a vegetarian meal into a vegan meal is usually not rocket science! Again, quick and easy substitutions, à la “or the plant-based milk of your choice”.
Recipes are presented in the format: ingredients, method, photo. Super simple (and no “chef’s nostalgic anecdote storytime” introductions that take more than, say, a sentence to tell).
All in all, a fabulous addition to anyone’s home kitchen!
Get your copy of “Pinch of Nom—Everyday Light” from Amazon today!
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Feta or Parmesan – Which is Healthier?
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Our Verdict
When comparing feta to parmesan, we picked the parmesan.
Why?
It’s close! Looking at the macros, parmesan has more protein and slightly less fat. Of the fat content, parmesan also has slightly less saturated fat, but neither of them are doing great in this category. Still, a relative win for parmesan.
In the category of vitamins, feta is a veritable vitamin-B-fest with more of vitamins B1, B2, B3, B5, B6, and B9. On the other hand, parmesan has more of vitamins A, B12, and choline. By strength of numbers, this is a win for feta.
Minerals tell a different story; parmesan has a lot more calcium, copper, iron, magnesium, manganese, phosphorus, potassium, selenium, and zinc. Meanwhile, feta is not higher in any minerals. A clear win for parmesan.
Both cheeses offer gut-healthy benefits (if consumed regularly in small portions), while neither are great for the heart.
On balance, we say parmesan wins the day.
Want to learn more?
You might like to read:
Feta Cheese vs Mozzarella – Which is Healthier?
Take care!
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Calculate (And Enjoy) The Perfect Night’s Sleep
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This is Dr. Michael Breus, a clinical psychologist and sleep specialist, and he wants you to get a good night’s sleep, every night.
First, let’s assume you know a lot of good advice about how to do that already in terms of environment and preparation, etc. If you want a recap before proceeding, then we recommend:
Get Better Sleep: Beyond The Basics
Now, what does he want to add?
Wake up refreshed
Of course, how obtainable this is will depend on the previous night’s sleep, but there is something important we can do here regardless, and it’s: beat sleep inertia.
Sleep inertia is what happens when we wake up groggy (for reasons other than being ill, drugged, etc) rather than refreshed. It’s not actually related to how much sleep we have, though!
Rather, it pertains to whether we woke up during a sleep cycle, or between cycles:
- If we wake up between sleep cycles, we’ll avoid sleep inertia.
- If we wake up during a sleep cycle, we’ll be groggy.
Deep sleep generally occurs in 90-minute blocks, albeit secretly that is generally 3× 20 minute blocks in a trenchcoat, with transition periods between, during which the brainwaves change frequency.
REM sleep generally occurs in 20 minute blocks, and will usually arrive in series towards the end of our natural sleep period, to fit neatly into the last 90-minute cycle.
Sometimes these will appear a little out of order, because we are complicated organic beings, but those are the general trends.
In any case, the take-away here is: interrupt them at your peril. You need to wake up between cycles. There are two ways you can do this:
- Carefully calculate everything, and set a very precise alarm clock (this will work so long as you are correct in guessing how long it will take you to fall asleep)
- Use a “sunrise” lamp alarm clock, that in the hour approaching your set alarm time, will gradually increase the light. Because the body will not naturally wake up during a cycle unless a threat is perceived (loud noise, physical rousing, etc), the sunrise lamp method means that you will wake up between sleep cycles at some point during that hour (towards the beginning or end, depending on what your sleep balance/debt is like).
Do not sleep in (even if you have a sleep debt); it will throw everything out.
Caffeine will not help much in the morning
Assuming you got a reasonable night’s sleep, your brain has been cleansed of adenosine (a sleepy chemical), and if you are suffering from sleep inertia, the grogginess is due to melatonin (a different sleepy chemical).
Caffeine is an adenosine receptor blocker, so that will do nothing to mitigate the effects of melatonin in your brain that doesn’t have any meaningful quantity of adenosine in it in the morning.
Adenosine gradually accumulates in the brain over the course of the day (and then gets washed out while we sleep), so if you’re sleepy in the afternoon (for reasons other than: you just had a nap and now have sleep inertia again), then caffeine can block that adenosine in the afternoon.
Of course, caffeine is also a stimulant (it increases adrenaline levels and promotes vasoconstriction), but its effects at healthily small doses are modest for most people, and you’d do better by splashing cold water on your face and/or listening to some upbeat music.
Learn more: The Two Sides Of Caffeine
Time your naps correctly (if you take naps)
Dr. Breus has a lot to say about this, based on a lot of clinical research, but as it’s entirely consistent with what we’ve written before (based on the exact same research), to save space we’ll link to that here:
How To Be An Expert Nap-Artist (With No “Sleep-Hangovers”)
Calculate your bedtime correctly
Remember what we said about sleep cycles? This means that that famous “7–9 hours sleep” is actually “either 7½ or 9 hours sleep”—because those are multiples of 90 minutes, whereas 8 hours (for example) is not.
So, consider the time you want to get up (ideally, this should be relatively early, and the same time every day), and then count backwards either 7½ or 9 hours sleep (you choose), add 20–30 minutes to fall asleep, and that’s your bedtime.
So for example: if you want to have 7½ hours sleep and get up at 6am, then your bedtime is anywhere between 10pm and 10:10pm.
Remember how we said not to sleep in, even if you have a sleep debt? Now is the time to pay it off, if you have one. If you normally sleep 7½ hours, then make tonight a 9-hour sleep (plus 20–30 minutes to fall asleep). This means you’ll still get up at 6am, but your bedtime is now anywhere between 8:30pm and 8:40pm.
Want to know more from Dr. Breus?
You might like this excellent book of his that we reviewed a while back:
The Power of When – by Dr. Michael Breus
Enjoy!
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Fatty Acids For The Eyes & Brain: The Good And The Bad
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Good For The Eyes; Good For The Brain
We’ve written before about omega-3 fatty acids, covering the basics and some lesser-known things:
What Omega-3 Fatty Acids Really Do For Us
…and while we discussed its well-established benefits against cognitive decline (which is to be expected, because omega-3 is good against inflammation, and a large part of age-related neurodegeneration is heavily related to neuroinflammation), there’s a part of the brain we didn’t talk about in that article: the eyes.
We did, however, talk in another article about supplements that benefit the eyes and [the rest of the] brain, and the important links between the two, to the point that an examination of the levels of lutein in the retina can inform clinicians about the levels of lutein in the brain as a whole, and strongly predict Alzheimer’s disease (because Alzheimer’s patients have significantly less lutein), here:
Now, let’s tie these two ideas together
In a recent (June 2024) meta-analysis of high-quality observational studies from the US and around the world, involving nearly a quarter of a million people over 40 (n=241,151), researchers found that a higher intake of omega-3 is significantly linked to a lower risk of macular degeneration.
To put it in numbers, the highest intake of omega-3s was associated with an 18% reduced risk of early stage macular degeneration.
They also looked at a breakdown of what kinds of omega-3, and found that taking a blend DHA and EPA worked best of all, although of people who only took one kind, DHA was the best “single type” option.
You can read the paper in full, here:
Association between fatty acid intake and age-related macular degeneration: a meta-analysis
A word about trans-fatty acids (TFAs)
It was another feature of the same study that, while looking at fatty acids in general, they also found that higher consumption of trans-fatty acids was associated with a higher risk of advanced age-related macular degeneration.
Specifically, the highest intake of TFAs was associated with a more than 2x increased risk.
There are two main dietary sources of trans-fatty acids:
- Processed foods that were made with TFAs; these have now been banned in a lot of places, but only quite recently, and the ban is on the processing, not the sale, so if you buy processed foods that contain ingredients that were processed before 2021 (not uncommon, given the long life of many processed foods), the chances of them having TFAs is higher.
- Most animal products. Most notably from mammals and their milk, so beef, pork, lamb, milk, cheese, and yes even yogurt. Poultry and fish technically do also contain TFAs in most cases, but the levels are much lower.
Back to the omega-3 fatty acids…
If you’re wondering where to get good quality omega-3, well, we listed some of the best dietary sources in our main omega-3 article (linked at the top of today’s).
However, if you want to supplement, here’s an example product on Amazon that’s high in DHA and EPA, following the science of what we shared today 😎
Take care!
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Unwell Women – by Dr. Elinor Cleghorn
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For a demographic that makes up a little over half of the world’s population, women are paradoxically marginalized in healthcare. And in other ways too, but this book is about health.
Dr. Cleghorn had to fight for seven (!) years to get her own lupus condition recognized as such, and continues to have to fight for it to be taken seriously on an ongoing basis. And yet, 95% of the book is not about her and her experiences, but rather, the bigger picture.
The book is divided into sections, by period in history. From Hippocrates to the modern day, Dr. Cleghorn gives us a well-researched, incredibly well-referenced overview of the marginalization of women’s health. Far from being a dry history book in the early parts though, it’s fascinating and engaging throughout.
The modern day sections are part shining a light into dark areas, part practical information-and-advice “did you know this happens, and you can do this about it”, and part emphatic call-to-action to demand better.
Bottom line: this book is in this reviewer’s “top 5 books read this year”, and we highly recommend it to you.
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Colloidal Gold’s Impressive Claims
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All That Glitters…
Today we’ll be examining colloidal gold supplementation.
This issue of 10almonds brought to you by the writer suddenly getting lots of advertisements for this supplement. It’s not a new thing though, and has been around in one form or another since pretty much forever.
Colloidal gold is…
- Gold, as in the yellow metal
- Colloidal, as in “very tiny insoluble particles dispersed though another substance (such as water)”
What are the claims made for it?
Honestly, just about everything is claimed for it. But to go with some popular claims:
- Reduces inflammation
- Supports skin health
- Boosts immune function
- Combats aging
- Improves cognitive function
So, what does the science say?
Does it do those things?
The short and oversimplified answer is: no
However, there is a little bit of tangential merit, so we’re going to talk about the science of it, and how the leap gets made between what the science says and what the advertisements say.
First… What makes gold so special, in general? Historically, three things:
- It’s quite rare
- It’s quite shiny
- It’s quite unreactive
- The first is about supply and demand, so that’s not very important to us in this article.
- The second is an aesthetic quality, which actually will have a little bit of relevance, but not much.
- The third has been important historically (because it meant that shiny gold stayed shiny, because it didn’t tarnish), and now also important industrially too, as gold can be used in many processes where we basically need for nothing to happen (i.e., a very inert component is needed)
That third quality—its unreactivity—has become important in medicine.
When scientists need a way to deliver something (without the delivering object getting eaten by the body’s “eat everything” tendencies), or otherwise not interact chemically with anything around, gold is an excellent choice.
Hence gold teeth, and gold fillings, by the way. They’re not just for the bling factor; they were developed because of their unreactivity and thus safety.
So, what about those health claims we mentioned above?
Here be science (creative interpretations not included)
The most-backed-by-science claim from that list is “reduces inflammation”.
Websites selling colloidal gold cite studies such as:
Gold nanoparticles reduce inflammation in cerebral microvessels of mice with sepsis
A promising title!The results of the study showed:
❝20 nm cit-AuNP treatment reduced leukocyte and platelet adhesion to cerebral blood vessels, prevented BBB failure, reduced TNF- concentration in brain, and ICAM-1 expression both in circulating polymorphonuclear (PMN) leukocytes and cerebral blood vessels of mice with sepsis. Furthermore, 20 nm cit-AuNP did not interfere with the antibiotic effect on the survival rate of mice with sepsis.❞
That “20 nm cit-AuNP” means “20 nm citrate-covered gold nanoparticles”
So it is not so much the antioxidant powers of gold being tested here, as the antioxidant powers of citrate, a known antioxidant. The gold was the carrying agent, whose mass and unreactivity allowed it to get where it needed to be.
The paper does say the words “Gold nanoparticles have been demonstrated to own important anti-inflammatory properties“ in the abstract, but does not elaborate on that, reference it, or indicate how.
Websites selling colloidal gold also cite papers such as:
Anti-inflammatory effect of gold nanoparticles supported on metal oxides
Another promising title! However the abstract mentions:
❝The effect was dependent on the MOx NPs chemical nature
[…]
The effect of Au/TiO2 NPs was not related to Au NPs size❞
MOx NPs = mineral oxide nanoparticles. In this case, the gold was a little more than a carrying agent, though, because the gold is described and explained as being a catalytic agent (i.e., its presence helps the attached mineral oxides react more quickly).
We said that was the most-backed claim, and as you can see, it has some basis but is rather tenuous since the gold by itself won’t do anything; it just helps the mineral oxides.
Next best-backed claim builds from that, which is “supports skin health”.
Sometimes colloidal gold is sold as a facial tonic. By itself it’ll distribute (inert) gold nanoparticles across your skin, and may “give you a healthy glow”, because that’s what happens when you put shiny wet stuff on your face.
Healthwise, if the facial tonic also contains some of the minerals we mentioned above, then it may have an antioxidant effect. But again, no minerals, no effect.
The claim that it “combats aging” is really a tag-on to the “antioxidant” claim.
As for the “supports immune health” claim… Websites selling colloid gold cite studies such as:
To keep things brief: gold can fight infectious diseases in much the same way that forks can fight hunger. It’s an inert carrying agent.
As for “improves cognitive function”? The only paper we could find cited was that mouse sepsis study again, this time with the website saying “researchers found that rats treated with colloidal gold showed improved spatial memory and learning ability“ whereas the paper cited absolutely did not claim that, not remotely, not even anything close to that. It wasn’t even rats, it was mice, and they did not test their memory or learning.
Is it safe?
Colloidal gold supplementation is considered very safe, precisely because gold is one of the least chemically reactive substances you could possibly consume. It is special precisely because it so rarely does anything.
However, impurities could be introduced in the production process, and the production process often involves incredibly harsh reagents to get the gold ions, and if any of those reagents are left in the solution, well, gold is safe but sodium borohydride and chloroauric acid aren’t!
Where can I get some?
In the unlikely event that our research review has given you an urge to try it, here’s an example product on Amazon
Take care!
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