The Circadian Rhythm: Far More Than Most People Know
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The Circadian Rhythm: Far More Than Most People Know
This is Dr. Satchidananda (Satchin) Panda, the scientist behind the discovery of the blue-light sensing cell type in the retina, and the many things it affects. But, he’s discovered more…
First, what you probably know (with a little more science)
Dr. Panda discovered that melanopsin, a photopigment, is “the primary candidate for photoreceptor-mediated entrainment”.
To put that in lay terms, it’s the brain’s go-to for knowing approximately what time of day or night it is, according to how much light there is (or isn’t), and how long it has (or hasn’t) been there.
But… the brain’s “go-to” isn’t the only method. By creating mice without melanopsin, he was able to find that they still keep a circadian rhythm, even in complete darkness:
Melanopsin (Opn4) Requirement for Normal Light-Induced Circadian Phase Shifting
In other words, it was a helpful, but not completely necessary, means of keeping a circadian rhythm.
So… What else is going on?
Dr. Panda and his team did a lot of science that is well beyond the scope of this main feature, but to give you an idea:
- With jargon: it explored the mechanisms and transcription translation negative feedback loops that regulate chronobiological processes, such as a histone lysine demathlyase 1a (JARID1a) that enhances Clock-Bmal1 transcription, and then used assorted genomic techniques to develop a model for how JARID1a works to moderate the level of Per transcription by regulating the transition between its repression and activation, and discovered that this heavily centered on hepatic gluconeogenesis and glucose homeostasis, facilitated by the protein cryptochrome regulating the fasting signal that occurs when glucagon binds to a G-protein coupled receptor, triggering CREB activation.
- Without jargon: a special protein tells our body how to respond to eating/fasting at different times of day—and conversely, certain physiological responses triggered by eating/fasting help us know what time of day it is.
- Simplest: our body keeps on its best cycle if we eat at the same time every day
This is important, because our circadian rhythm matters for a lot more than sleeping/waking! Take hormones, for example:
- Obvious hormones: testosterone and estrogen peak in the mornings around 9am, progesterone peaks between 10pm and 2am
- Forgotten hormones: cortisol peaks in the morning around 8:30am, melatonin peaks between 10pm and 2am
- More hormones: ghrelin (hunger hormone) peaks around 10am, leptin (satiety hormone) peaks 20 minutes after eating a certain amount of satiety-triggering food (protein does this most quickly), insulin is heavily tied to carbohydrate intake, but will still peak and trough according to when the body expects food.
What does this mean for us in practical terms?
For a start, it means that intermittent fasting can help guard against metabolic and related diseases (including inflammation, and thus also cancer, diabetes, arthritis, and more) a lot more if we practice it with our circadian rhythm in mind.
So that “8-hour window” for eating, that many intermittent fasting practitioners adhere to, is going to do much, much better if it’s 10am to 6pm, rather than, say, 4pm to midnight.
Additionally, Dr. Panda and his team found that a 12-hour eating window wasn’t sufficient to help significantly.
Some other take-aways:
- For reasons beyond the scope of this article, it’s good to exercise a) early b) before eating, so getting in some exercise between 8.30am and 10am is ideal
- It also means it’s beneficial to “front-load” eating, so a large breakfast at 10am, and smaller meals/snacks afterwards, is best.
- It also means that getting sunlight (even if cloud-covered) around 8.30am helps guard against metabolic disorders a lot, since the light remains the body’s go-to way of knowing the time.
- We realize that sunlight is not available at 8.30am at all latitudes at all times of year. Artificial is next-best.
- It also means sexual desire will typically peak in men in the mornings (per testosterone) and women in the evenings (per progesterone), but this is just an interesting bit of trivia, and not so relevant to metabolic health
What to do next…
Want to stabilize your own circadian rhythm in the best way, and also help Dr. Panda with his research?
His team’s (free!) app, “My Circadian Clock”, can help you track and organize all of the body’s measurable-by-you circadian events, and, if you give permission, will contribute to what will be the largest-yet human study into the topics covered today, to refine the conclusions and learn more about what works best.
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Fitness In Our Fifties
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It’s Q&A Day at 10almonds!
Have a question or a request? We love to hear from you!
In cases where we’ve already covered something, we might link to what we wrote before, but will always be happy to revisit any of our topics again in the future too—there’s always more to say!
As ever: if the question/request can be answered briefly, we’ll do it here in our Q&A Thursday edition. If not, we’ll make a main feature of it shortly afterwards!
So, no question/request too big or small
Q: What’s a worthwhile fitness goal for people in their 50s?
A: At 10almonds, we think that goals are great but habits are better.
If your goal is to run a marathon, that’s a fine goal, and can be very motivating, but then after the marathon, then what? You’ll look back on it as a great achievement, but what will it do for your future health?
PS, yes, marathon-running in one’s middle age is a fine and good activity for most people. Maybe skip it if you have osteoporosis or some other relevant problem (check with your doctor), but…
Marathons in Mid- and Later-Life ← we wrote about the science of it here
PS, we also explored some science that may be applicable to your other question, on the same page as that about marathons!
The thing about habits vs goals is that habits give ongoing cumulative (often even: compounding) benefits:
How To Really Pick Up (And Keep!) Those Habits
If you pressingly want advice on goals though, our advice is this:
Make it your goal to be prepared for the health challenges of later life. It may seem gloomy to say that old age is coming for us all if something else doesn’t get us first, but the fact is, old age does not have to come with age-related decline, and the very least, we can increase our healthspan (so we’re hitting 90 with most of the good health we enjoyed in our 70s, for example, or hitting 80 with most of the good health we enjoyed in our 60s).
If that goal seems a little wishy-washy, here are some very specific and practical ideas to get you started:
Train For The Event Of Your Life!
As for the limits and/or extents of how much we can do in that regard? Here are what two aging experts have to say:
And here’s what we at 10almonds had to say:
Age & Aging: What Can (And Can’t) We Do About It?
Take care!
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Age & Aging: What Can (And Can’t) We Do About It?
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How old do you want to be?
We asked you how old you are, and got an interesting spread of answers. This wasn’t too surprising; of course we have a general idea of who our readership is and we write accordingly.
What’s interesting is the gap for “40s”.
And, this wasn’t the case of a broken poll button, it’s something that crops up a lot in health-related sociological research. People who are most interested in taking extra care of their body are often:
- Younger people full of optimism about maintaining this perfectly healthy body forever
- Older people realizing “if I don’t want to suffer avoidable parts of age-related decline, now is the time to address these things”
In between, we often have a gap whereby people no longer have the optimism of youth, but do not yet feel the pressure of older age.
Which is not to say there aren’t 40-somethings who do care! Indeed, we know for a fact we have some subscribers in their 40s (and some in their 90s, too), just, they evidently didn’t vote in this poll.
Anyway, let’s bust some myths…
Aging is inevitable: True or False?
False, probably. That seems like a bold (and fortune-telling) claim, so let’s flip it to deconstruct it more logically:
Aging is, and always will be, unstoppable: True or False?
That has to be “False, probably”. To say “true” now sounds like an even bolder claim. Just like “the moon will always be out of reach”.
- When CPR was first developed, first-aiders were arrested for “interfering with a corpse”.
- Many diseases used to be death sentences that are now “take one of these in the morning”
- If you think this is an appeal to distant history, HIV+ status was a death sentence in the 90s. Now it’s “take one of these in the morning”.
But, this is an appeal to the past, and that’s not always a guarantee of the future. Where does the science stand currently? How is the research and development doing on slowing, halting, reversing aging?
We can slow aging: True or False?
True! There’s a difference between chronological age (i.e., how much time has passed while we’ve been alive) and biological age (i.e., what our diverse markers of aging look like).
Biological age often gets talked about as a simplified number, but it’s more complex than that, as we can age in different ways at different rates, for example:
- Visual markers of aging (e.g. wrinkles, graying hair)
- Performative markers of aging (e.g. mobility tests)
- Internal functional markers of aging (e.g. tests for cognitive decline, eyesight, hearing, etc)
- Cellular markers or aging (e.g. telomere length)
- …and more, but we only have so much room here
There are things we can do to slow most of those, including:
- Good nutrition (e.g. collagen and lutein, to keep specific parts of the body functioning “like those of a younger person” ranging from the joints to the eyes and brain)
- Anti-oxidant activity (e.g. eating anti-oxidant foods, supplementing with anti-oxidants or other things that mitigate oxidative stress, and avoiding foods that hasten oxidative stress which causes many kinds of aging)
- Getting good sleep (not to be underestimated for its restorative importance)
- Taking care of our cognitive health
- Taking care of our mental health (especially: reducing stress)
- Taking care of our mobility (prevention is better than cure!)
In the case of cognitive decline particularly, check out our previous article:
How To Reduce Your Alzheimer’s Risk
It’s too early to worry about… / It’s too late to do anything about… True or False?
False and False!
Many things that affect our health later in life are based on early-life choices and events. So it’s important for young people to take advantage of that. The earlier one adopts a healthy lifestyle, the better, because, and hold onto your hats for the shocker here: aging is cumulative.
However, that doesn’t mean that taking up healthy practices (or dropping unhealthy ones) is pointless later in life, even in one’s 70s and beyond!
Read about this and more from the National Institute of Aging:
What Do We Know About Healthy Aging?
We can halt aging: True or False?
False, for now at least. Our bodies are not statues; they are living organisms, constantly rebuilding themselves, constantly changing, every second of every day, for better or for worse. Every healthy or unhealthy choice you make, every beneficial or adverse experience you encounter, affects your body on a cellular level.
Your body never, ever, stops changing for as long as you live.
But…
We can reverse aging: True or False?
True! Contingently and with limitations, for now at least.
Remember what we said about your body constantly rebuilding itself? That goes for making itself better as well as making itself worse.
- If yesterday you couldn’t touch your toes and today you can, congratulations, you just got younger by a biological marker of aging.
- If you stopped drinking/smoking/eating a certain way last year, and this year your skin has fewer wrinkles, congratulations, you got younger by a biological marker of aging.
- If you’ve been exercising and now your heart rate variability and VO2 max are better than last month, congratulations, you got younger by a biological marker aging.
- If you took supplements that reduce and/or mitigate oxidative stress (e.g. resveratrol, CoQ10, l-theanine, etc), and you took up intermittent fasting, and now your telomeres are longer than they were six months ago, congratulations, you got younger by a biological marker of aging.
But those aren’t really being younger, we’ll still die when our time is up: True or False?
False and True, respectively.
Those kinds of things are really being younger, biologically. What else do you think being biologically younger is?
We may indeed die when our time is up, but (unless we suffer fatal accident or incident first) “when our time is up” is something that is decided mostly by the above factors.
Genetics—the closest thing we have to biological “fate”—accounts for only about 25% of our longevity-related health*.
Genes predispose, but they don’t predetermine.
*Read more: Human longevity: Genetics or Lifestyle? It takes two to tango
(from the Journal of Immunity and Ageing)
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Kiwi vs Lemon – Which is Healthier?
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Our Verdict
When comparing kiwi to lemon, we picked the kiwi.
Why?
A fairly straightforward one today!
In terms of macros, kiwi has more protein, carbs, and fiber, the ratio of the latter two also giving it the lower glycemic index. An easy win for kiwi here.
In the category of vitamins, kiwi has more of vitamins A, B2, B3, B9, C, E, K, and choline, while lemon has more of vitamins B1 and B6. Yes, that’s right, lemon didn’t even win on the vitamin C that it’s famous for. In any case, a clear 8:2 win for kiwi.
Looking at minerals, kiwi has more calcium, copper, magnesium, manganese, phosphorus, potassium, and zinc, while lemon has more iron and selenium. So, looking at this 7:2 win for kiwi, you might want to reconsider that “glass of lemon water to replenish minerals” trend!
None of this is to knock lemons, by the way; lemons are still a very respectable fruit, nutritionally. Probably very few people are out there eating lemons the way one might eat kiwi…
(writer’s note: I say “very few”, as once upon a time when my son was small, I remember coming into the kitchen to find he had helped himself to lemon wedges and was just eating them, so it can happen. But I also one time when he was just as small, found him drinking hot sauce directly from the bottle, so hey, he clearly already enjoyed strong flavors. Lest I seem a very inattentive mother, I’ll say in my defense that our kitchen has no real toddler-height hazards when the oven is cold, and those items were from the bottom of the fridge, so easy to access if I leave the room for a moment to grab something)
…but what we do want to say here is: if you don’t care for lemons so much, you’re not missing out. If the lemon water isn’t calling to you, you can skip it guilt-free.
In any case, do enjoy either or both, but kiwi’s the clear winner here!
Want to learn more?
You might like to read:
Top 8 Fruits That Prevent & Kill Cancer ← kiwi is top of the list! It has some cool properties, as you’ll see, killing cancer cells while sparing healthy ones.
Take care!
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What is ‘breathwork’? And do I need to do it?
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From “breathwork recipes” to breathing techniques, many social media and health websites are recommending breathwork to reduce stress.
But breathwork is not new. Rather it is the latest in a long history of breathing techniques such as Pranayama from India and qigong from China. Such practices have been used for thousands of years to promote a healthy mind and body.
The benefits can be immediate and obvious. Try taking a deep breath in through your nose and exhaling slowly. Do you feel a little calmer?
So, what’s the difference between the breathing we do to keep us alive and breathwork?
Taras Grebinets/Shutterstock Breathwork is about control
Breathwork is not the same as other mindfulness practices. While the latter focus on observing the breath, breathwork is about controlling inhalation and exhalation.
Normally, breathing happens automatically via messages from the brain, outside our conscious control. But we can control our breath, by directing the movement of our diaphragm and mouth.
The diaphragm is a large muscle that separates our thoracic (chest) and abdominal (belly) cavities. When the diaphragm contracts, it expands the thoracic cavity and pulls air into the lungs.
Controlling how deep, how often, how fast and through what (nose or mouth) we inhale is the crux of breathwork, from fire breathing to the humming bee breath.
Breathwork can calm or excite
Even small bits of breathwork can have physical and mental health benefits and complete the stress cycle to avoid burnout.
Calming breathwork includes diaphragmatic (belly) breathing, slow breathing, pausing between breaths, and specifically slowing down the exhale.
In diaphragmatic breathing, you consciously contract your diaphragm down into your abdomen to inhale. This pushes your belly outwards and makes your breathing deeper and slower.
You can also slow the breath by doing:
- box breathing (count to four for each of four steps: breathe in, hold, breathe out, hold), or
- coherent breathing (controlled slow breathing of five or six breaths per minute), or
- alternate nostril breathing (close the left nostril and breathe in slowly through the right nostril, then close the right nostril and breathe out slowly through the left nostril, then repeat the opposite way).
You can slow down the exhalation specifically by counting, humming or pursing your lips as you breathe out.
In contrast to these calming breathing practices, energising fast-paced breathwork increases arousal. For example, fire breathing (breathe in and out quickly, but not deeply, through your nose in a consistent rhythm) and Lion’s breath (breathe out through your mouth, stick your tongue out and make a strong “haa” sound).
What is happening in the body?
Deep and slow breathing, especially with a long exhale, is the best way to stimulate the vagus nerves. The vagus nerves pass through the diaphragm and are the main nerves of the parasympathetic nervous system.
Simulating the vagus nerves calms our sympathetic nervous system (fight or flight) stress response. This improves mood, lowers the stress hormone cortisol and helps to regulate emotions and responses. It also promotes more coordinated brain activity, improves immune function and reduces inflammation.
Taking deep, diaphragmatic breaths also has physical benefits. This improves blood flow, lung function and exercise performance, increases oxygen in the body, and strengthens the diaphragm.
Slow breathing reduces heart rate and blood pressure and increases heart rate variability (normal variation in time between heart beats). These are linked to better heart health.
Taking shallow, quick, rhythmic breaths in and out through your nose stimulates the sympathetic nervous system. Short-term, controlled activation of the stress response is healthy and develops resilience to stress.
Breathing in through the nose
We are designed to inhale through our nose, not our mouth. Inside our nose are lots of blood vessels, mucous glands and tiny hairs called cilia. These warm and humidify the air we breathe and filter out germs and toxins.
We want the air that reaches our airways and lungs to be clean and moist. Cold and dry air is irritating to our nose and throat, and we don’t want germs to get into the body.
Nasal breathing increases parasympathetic activity and releases nitric oxide, which improves airway dilation and lowers blood pressure.
Consistently breathing through our mouth is not healthy. It can lead to pollutants and infections reaching the lungs, snoring, sleep apnoea, and dental issues including cavities and jaw joint problems.
Breathing can be high and shallow when we are stressed. mi_viri/Shutterstock A free workout
Slow breathing – even short sessions at home – can reduce stress, anxiety and depression in the general population and among those with clinical depression or anxiety. Research on breathwork in helping post-traumatic stress disorder (PTSD) is also promising.
Diaphragmatic breathing to improve lung function and strengthen the diaphragm can improve breathing and exercise intolerance in chronic heart failure, chronic obstructive pulmonary disease and asthma. It can also improve exercise performance and reduce oxidative stress (an imbalance of more free radicals and/or less antioxidants, which can damage cells) after exercise.
Waiting at the lights? This could be your signal to do some breathwork. doublelee/Shutterstock A mind-body connection you can access any time
If you feel stressed or anxious, you might subconsciously take shallow, quick breaths, but this can make you feel more anxious. Deep diaphragmatic breaths through your nose and focusing on strong exhalations can help break this cycle and bring calm and mental clarity.
Just a few minutes a day of breathwork can improve your physical and mental health and wellbeing. Daily deep breathing exercises in the workplace reduce blood pressure and stress, which is important since burnout rates are high.
Bottom line: any conscious control of your breath throughout the day is positive.
So, next time you are waiting in a line, at traffic lights or for the kettle to boil, take a moment to focus on your breath. Breathe deeply into your belly through your nose, exhale slowly, and enjoy the benefits.
Theresa Larkin, Associate professor of Medical Sciences, University of Wollongong and Judy Pickard, Senior Lecturer, Clinical Psychology, University of Wollongong
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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The 6 Dimensions Of Sleep (And Why They Matter)
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How Good Is Your Sleep, Really?
This is Dr. Marie-Pierre St-Onge, Director of Columbia University’s Center of Excellence for Sleep and Circadian Research.
The focus of Dr. St-Onge’s research is the study of the impact of lifestyle, especially sleep and diet, on cardio-metabolic risk factors.
She conducts clinical research combining her expertise on sleep, nutrition, and energy regulation.
What kind of things do her studies look at?
Her work focuses on questions about…
- The role of circadian rhythms (including sleep duration and timing)
- Meal timing and eating patterns
…and their impact on cardio-metabolic risk.
What does she want us to know?
First things first, when not to worry:
❝Getting a bad night’s sleep once in a while isn’t anything to worry about. That’s what we would describe as transient insomnia. Chronic insomnia occurs when you spend three months or more without regular sleep, and that is when I would start to be concerned.❞
But… as prevention is (as ever) better than cure, she also advises that we do pay attention to our sleep! And, as for how to do that…
The Six Dimensions of Sleep
One useful definition of overall sleep health is the RU-Sated framework, which assesses six key dimensions of sleep that have been consistently associated with better health outcomes. These are:
- regularity
- satisfaction with sleep
- alertness during waking hours
- timing of sleep
- efficiency of sleep
- duration of sleep
You’ll notice that some of these things you can only really know if you use a sleep-monitoring app. She does recommend the use of those, and so do we!
We reviewed and compared some of the most popular sleep-monitoring apps! You can check them out here: Time For Some Pillow Talk
You also might like…
We’re not all the same with regard to when is the best time for us to sleep, so:
Use This Sleep Cycle Calculator To Figure Out the Optimal Time for You To Go to Bed and Wake Up
AROUND THE WEB
What’s happening in the health world…
- Aspirin may make your breathing worse
- Taking naps for more than 30 minutes may raise your metabolic disease risk
- How to ease back into exercise after surgery
- Study provides evidence that breathing exercises may reduce your Alzheimer’s risk
- No one in movies knows how to swallow a pill
More to come tomorrow!
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The Bitter Truth About Coffee (or is it?)
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The Bitter Truth About Coffee (or is it?)
Yesterday, we asked you for your (health-related) views on coffee. The results were clear: if we assume the responses to be representative, we’re a large group of coffee-enthusiasts!
One subscriber who voted for “Coffee is a healthy stimulant, hydrating, and full of antioxidants” wrote:
❝Not so sure about how hydrating it is! Like most food and drink, moderation is key. More than 2 or 3 cups make me buzz! Just too much.❞
And that fine point brings us to our first potential myth:
Coffee is dehydrating: True or False?
False. With caveats…
Coffee, in whatever form we drink it, is wet. This may not come as a startling revelation, but it’s an important starting point. It’s mostly water. Water itself is not dehydrating.
Caffeine, however, is a diuretic—meaning you will tend to pee more. It achieves its diuretic effect by increasing blood flow to your kidneys, which prompts them to release more water through urination.
See: Effect of caffeine on bladder function in patients with overactive bladder symptoms
How much caffeine is required to have a diuretic effect? About 4.5 mg/kg.
What this means in practical terms: if you weigh 70kg (a little over 150lbs), 4.5×70 gives us 315.
315mg is about how much caffeine might be in six shots of espresso. We say “might” because while dosage calculations are an exact science, the actual amount in your shot of espresso can vary depending on many factors, including:
- The kind of coffee bean
- How and when it was roasted
- How and when it was ground
- The water used to make the espresso
- The pressure and temperature of the water
…and that’s all without looking at the most obvious factor: “is the coffee decaffeinated?”
If it doesn’t contain caffeine, it’s not diuretic. Decaffeinated coffee does usually contain tiny amounts of caffeine still, but with nearer 3mg than 300mg, it’s orders of magnitude away from having a diuretic effect.
If it does contain caffeine, then the next question becomes: “and how much water?”
For example, an Americano (espresso, with hot water added to make it a long drink) will be more hydrating than a ristretto (espresso, stopped halfway through pushing, meaning it is shorter and stronger than a normal espresso).
A subscriber who voted for “Coffee messes with sleep, creates dependency, is bad for the heart and gut, and is dehydrating too” wrote:
❝Coffee causes tachycardia for me so staying away is best. People with colon cancer are urged to stay away from coffee completely.❞
These are great points! It brings us to our next potential myth:
Coffee is bad for the heart: True or False?
False… For most people.
Some people, like our subscriber above, have an adverse reaction to caffeine, such as tachycardia. An important reason (beyond basic decency) for anyone providing coffee to honor requests for decaff.
For most people, caffeine is “heart neutral”. It doesn’t provide direct benefits or cause direct harm, provided it is enjoyed in moderation.
See also: Can you overdose on caffeine?
Some quick extra notes…
That’s all we have time for in myth-busting, but it’s worth noting before we close that coffee has a lot of health benefits; we didn’t cover them today because they’re not contentious, but they are interesting nevertheless:
- Coffee is the world’s biggest source of antioxidants
- 65% reduced risk of Alzheimer’s for coffee-drinkers
- 67% reduced risk of type 2 diabetes for coffee-drinkers
- 43% reduced risk of liver cancer for coffee-drinkers
- 53% reduced suicide risk for coffee-drinkers
Enjoy!
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