So That's Why

Vegetology

You've been told to drink eight glasses of water a day. You've chased 10,000 steps like it's some kind of biological law. You've checked your cholesterol without being entirely sure what you're actually checking for. Most health content tells you what to do. Nobody explains why. That's the gap So That's Why was made to fill. Each week, Jen, Chris, and Matt take one everyday health question — the kind that's been nagging at the back of your mind, or that you've just accepted without thinking — and unpack the actual science behind it. Where did this idea come from? What's really happening inside your body? And does the evidence actually hold up? What they find is often surprising. The 10,000-steps rule was invented by a Japanese marketing team in 1964. The eight-glasses-of-water recommendation came from a misread document. The reason some people turn tomato-red when they exercise has nothing to do with fitness — it's about blood vessel density. The thing that makes you cry when you chop onions was only properly understood in 2002. Cholesterol is in every single cell of your body — so why the terrible reputation? The science is real, the research is specific, and the conversations are genuinely fascinating. And the three people having them have the backgrounds to get it right. Jen holds a PhD in biochemistry and molecular biology. She asks the questions you're thinking — informed ones, not naive ones — and keeps the conversation grounded in the human experience of all this biology. Chris is a formulation scientist with over 30 years of experience. He's read the studies, knows the mechanisms, and has the analogies that make complex biology actually click. Matt looks at the science and asks what it means for real people, with real lives, real schedules, and no time for perfectionism. Together they hit that sweet spot between too technical to understand and so simplified it's not actually true anymore. Getting there, it turns out, is harder than it sounds. So That's Why doesn't give you a list of rules to follow. It doesn't shame you for the things you haven't been doing. It explains the mechanism — the actual biology — so you can make decisions that fit your life, rather than just following advice that might not apply to you at all. Episodes run about 20 minutes. They're built for commutes, workouts, or cooking dinner. By the end of each one, you'll be able to explain the answer to someone else — which is the whole point. New episodes every week. Subscribe and find out why.

  1. 5d ago

    Why Do We Feel Tired After Eating?

    Your lunch is quietly manufacturing sleep hormone — and that is only half of what is happening. In this episode, Jen, Chris, and Jamie unpack the real biology behind post-meal tiredness, from the brain neurons that food literally switches off to the circadian dip that amplifies everything. Episode Summary The post-lunch slump has a proper name — postprandial somnolence — and a surprisingly fascinating set of causes. Research shows it affects the majority of people to some degree, with measurable drops in reaction time, attention, and the ability to absorb new information in the post-meal window. In this episode, the team breaks down the full cascade of biological mechanisms at work, explains why meal composition and timing matter so much, and offers practical strategies for managing your afternoon without needing a nap. Timestamps 00:00 — Introduction01:27 — The productivity cost of the post-lunch dip02:39 — Tryptophan, serotonin, and your lunch-triggered melatonin04:10 — The brain neurons that food switches off04:41 — Rest and digest mode explained06:30 — Why your body clock makes everything worse07:23 — How what you eat changes how hard the dip hits08:41 — Practical ways to beat the afternoon slump Key PointsYour Body Is Running a Melatonin Production Line at Lunchtime(02:39) When you eat carbohydrates, your pancreas releases insulin to move glucose into your cells. But insulin is doing something else simultaneously — it clears competing amino acids from the bloodstream, giving tryptophan a much clearer path across the blood-brain barrier. Once tryptophan reaches the brain, it converts to serotonin, and some of that serotonin becomes melatonin — the hormone that signals it is time to sleep. "Your lunchtime pasta is essentially manufacturing sleep hormone. Your body's running a melatonin production line and you didn't know." — JamieFood Silences Your Brain's Stay-Awake Neurons(04:10) The melatonin pathway is only half the picture. Your brain contains orexin neurons in the lateral hypothalamus — one of its primary wakefulness signals. Research has shown that rising blood glucose after a meal directly silences these neurons. The result is a double mechanism: sleep hormone production goes up at the same time that the brain's own alertness signal is turned down. "You've got a double hit. You're increasing the ingredients for sleep hormones while simultaneously turning down the volume on your brain's wakefulness signal." — JenMeals and Circadian Timing Stack on Top of Each Other(06:30) Your body has a natural dip in alertness between roughly 1pm and 3pm regardless of whether you have eaten. Research shows that food does not cause this afternoon slump — it amplifies it. One study found that eating increased the duration of an afternoon nap but did not initiate one. For most people, lunchtime falls directly in this window, which is why the post-meal dip feels so pronounced. The Most Practical Changes Are Also the Most Impactful(08:41) Meal composition is the single biggest lever. Complex carbohydrates, lean protein, healthy fats, and fibre slow glucose absorption and produce a gentler hormonal response. A short post-meal walk — even 10 to 15 minutes — improves blood circulation, stimulates glucose uptake by the muscles, and counteracts the parasympathetic shift. Bright natural light in the afternoon has also been shown to reduce the post-lunch dip. "Loads of cultures build this into their daily routine already. We've somehow engineered it out of our day by eating at our desks and going straight back to our computer screens." — JamieAbout So That's WhySo That's Why is a weekly podcast where Jen, Chris, and Jamie unpack the science behind everyday health questions. No jargon, no judgment — just genuine curiosity and proper research.

    13 min

  2. Jun 25

    Why Do We Yawn and Why Is It So Contagious?

    Yawning has nothing to do with oxygen. It's your brain's built-in cooling system, and the contagious version taps into the same neural circuitry as empathy. In this episode, Jen, Chris, and Matt unpack the surprisingly complex science behind one of the most universal human experiences. They dismantle the oxygen myth with the research that disproved it, explain the brain temperature regulation theory and how it works mechanically, explore why contagious yawning is observed across species from chimpanzees to parakeets, and cover what excessive yawning might be signalling. By the end, a habit most people spend energy feeling embarrassed about looks considerably more interesting. Timestamps 00:00 - Introduction 00:41 - What actually happens when you yawn 02:46 - The oxygen myth debunked 04:18 - Why your brain uses yawning to cool down 06:58 - Why yawning is contagious 09:42 - The psychopathy connection 11:48 - When excessive yawning is worth paying attention to 13:21 - So that's why The Oxygen Theory Has Been Disproved (00:02:46)The most persistent explanation for yawning is that the body is correcting low oxygen or high carbon dioxide. It's also wrong. A study published in the journal Physiology and Behavior manipulated the oxygen and carbon dioxide content of the air participants were breathing and found it made no difference at all to how often they yawned. As Chris puts it in the episode, it's "a great example of a fact that survives purely on confidence." Your Brain Has a Thermostat Problem (00:04:18)The leading current theory centres on brain temperature regulation. The brain operates within a narrow temperature window, and yawning appears to be one of its tools for staying there. A researcher at Princeton University found that holding warm packs to the forehead significantly increased yawning frequency, while cool packs reduced it below baseline. The mechanism: the deep inhale draws cooler air across the palate, which sits directly beneath the brain, while jaw muscle stretching increases local blood flow. Both effects work together to cool the surrounding tissue. "It's basically a built-in cooling fan, like a car radiator for the brain." — MattIt also explains why athletes yawn before competing (the brain is ramping up and getting ahead of the heat), why yawning clusters around waking and falling asleep (brain temperature is shifting), and why yawning appears in foetuses at just 11 weeks of gestation, long before the lungs are functional. Why Catching a Yawn Is Linked to Empathy (00:06:58)Contagious yawning has been documented in humans, chimpanzees, wolves, dogs, and parakeets. In social animals, it appears to synchronise group alertness and brain state. In humans, it seems to involve mirror neuron systems: the same neural circuitry underlying empathy and social imitation. Research in a psychology journal found a positive connection between empathy scores and susceptibility to contagious yawning, though a Duke University study with over 300 participants found the correlation was less consistent than earlier, smaller studies suggested. The link may be real, but more modest than some headlines have implied. "The empathy link may be real, but more modest than the headlines made it sound. Which is a pattern that comes up regularly when smaller psychology findings get replicated at a larger scale." — JenWhen Yawning Is a Signal Worth Noticing (00:11:48)Occasional yawning is completely normal. Excessive yawning, particularly when unprompted by tiredness, can occasionally be associated with migraines, epilepsy, or in rare cases cardiac or neurological events. More commonly, a noticeable uptick in yawning is simply the brain flagging that sleep quality has dipped. "It's a bit like how your body uses pain as a signal. You don't ignore it entirely, but you also don't panic every time your knee aches after a long walk." — MattAbout So That's WhySo That's Why is a weekly podcast where Jen, Chris, and Matt unpack the science behind everyday health questions. No jargon, no judgment, just genuine curiosity and proper research.

    17 min

  3. Jun 18

    Why Do Wednesdays Feel Harder Than Mondays?

    Everyone complains about Mondays. Turns out we've been blaming the wrong day entirely. Researchers who analysed 2.4 million social media posts and blogs found that Monday is actually the second happiest day of the week. Wednesday scored lowest for happiness — consistently. In this episode, Jen, Chris, and Matt explore why the midweek slump is real, what the science tells us about the likely causes, and what you can actually do with that information. Timestamps 00:00 — Introduction 01:00 — The research that flips the Monday myth 02:08 — Why the middle days blur together 03:26 — Being honest about what the science does and doesn't show 04:22 — Sleep debt and decision fatigue 07:09 — Stuck in no man's land 09:22 — What might actually help Key TakeawaysMonday's bad reputation isn't backed by dataThe University of Vermont analysed over 2.4 million social media posts and internet blogs, scoring the emotional content of language used throughout the week. Wednesday consistently scored lowest for happiness. Monday ranked second highest, just behind Friday. As Matt puts it in the episode: "So we've been blaming Monday this whole time, and Wednesday was quietly being the worst." Your brain has fewer anchors for midweek daysA study from the University of Lincoln found that almost 40% of participants confused the current day with the one before or after it — and those errors clustered heavily around Tuesday, Wednesday, and Thursday. Participants could correctly identify Monday or Friday twice as fast as they could identify Wednesday. Chris explains that Monday and Friday carry strong psychological associations — fresh starts and anticipated freedom — while the middle days blur into one indistinct block with fewer cognitive anchors. Three pressures peak at the same time on WednesdayThe team is upfront that Wednesday-specific research is limited. What does exist is robust evidence on three separate phenomena that likely converge at midweek: accumulated sleep debt (the average adult sleeps over half an hour less on weeknights, and research suggests it takes up to four days to recover from a single hour of lost sleep), decision fatigue (every choice made since Monday draws from a finite mental resource that doesn't refill during the working day), and temporal distance from rest (Wednesday sits at the maximum psychological distance from both weekends, with no positive residue from the last and no real anticipation of the next). Understanding this gives you something to work withJen summarises it well: "When you understand that accumulated sleep debt is a real phenomenon, and decision fatigue is a real phenomenon, and psychological distance from rest is a real phenomenon — you don't need a specific Wednesday study to understand why midweek might be when all of these converge." Practical starting points include protecting sleep consistency across the week, saving complex decisions for earlier in the week when mental resources are fresher, and building small things to look forward to midweek to break up the psychological stretch between weekends. About So That's WhySo That's Why is a weekly podcast where Jen, Chris, and Matt unpack the science behind everyday health questions. No jargon, no judgment — just genuine curiosity and proper research.

    13 min

  4. Jun 11

    Why Do Adults Still Get Acne?

    Most people assume acne ends with their teenage years. The science says otherwise — and the reason it keeps coming back has nothing to do with dirty skin. In this episode, Jen, Chris, and Matt unpack the four biological processes behind every breakout and explain why they don't simply stop at the end of puberty. They cover the adult-specific triggers — hormonal shifts, cortisol, and diet — and bust two of the most persistent myths in skincare: that pores open and close, and that acne means your skin isn't clean. They also walk through what the evidence says actually works for treatment, including the timeline that most people get wrong, and reframe acne as a whole-body symptom rather than a surface skin issue. Timestamps 00:00 — Introduction 00:24 — The four biological processes behind every breakout 02:42 — The pores opening and closing myth, busted 05:29 — Why adult acne is triggered differently to teenage acne 08:29 — Diet, blood sugar, and the IGF-1 connection 12:04 — Why acne has nothing to do with dirty skin 13:33 — Treatments that work (and the timeline most people get wrong) 17:04 — Acne as a whole-body symptom Four Things Have to Go Wrong at Once[00:24] Acne isn't a surface issue. It starts inside the hair follicle, and for a breakout to develop, four processes have to align: excess sebum production driven by androgens; abnormal, sticky skin cell shedding that blocks the pore from the inside; bacterial overgrowth of C. acnes in the clogged follicle; and an immune-driven inflammatory response that creates the redness and swelling. As Matt put it: "It's like a project, isn't it? Without a project manager, everyone's doing their own thing and the outcome just seems to be mayhem and chaos." Those four processes are identical in teenagers and adults. What changes is what sets them off. Adult Triggers Are Different from Teenage Ones[05:29] In puberty, a steady surge in androgens drives acne. In adult life, it's the irregular hormonal shifts that cause problems. For women, cyclical acne tied to the menstrual cycle is the most common pattern, with breakouts clustering around the jawline and lower face — a location so consistent that persistent lower face acne in adult women is now treated as a hormonal flag in dermatology. Stress is a separate but significant driver. As Chris explained: "I'd say less of a case of stress creating acne from nothing. More like stress lowering the threshold at which everything that was already kind of quietly ticking over tips over the edge into a full on breakout." Diet runs through blood sugar: high-glycaemic foods trigger an IGF-1 spike that directly stimulates the sebaceous glands. A 2023 review found a consistent link between high-glycaemic diets and acne severity, particularly in adult women. Treatment Requires More Patience Than Most People Give It[13:33] Three over-the-counter actives have solid evidence behind them: benzoyl peroxide, salicylic acid, and adapalene. But the timeline is where most people go wrong. As Jen noted: "Most of them require a minimum of about six to eight weeks for any noticeable improvement, and three months really to properly evaluate its effectiveness." Treatments should be introduced one at a time — combining actives makes it impossible to know what's working and risks significant irritation. If consistent treatment over two to three months hasn't made a difference, or if acne is leaving scarring, it's worth a conversation with a doctor. Research has shown that adult acne significantly affects quality of life and self-esteem — and that alone is a legitimate reason to seek proper support. Acne Is a Whole-Body Symptom[17:04] The inputs behind acne — hormones, cortisol, blood sugar, systemic inflammation — are whole-body processes. The skin is simply where they become visible. As Chris put it: "The skin is the body's largest organ, but it's also the one we can see. So it can reflect things going on elsewhere in the body." Poor sleep, for instance, elevates cortisol directly, feeding into both sebum production and cellular inflammation. The lifestyle factors that support skin health are largely the same ones that support broader health outcomes. About So That's WhySo That's Why is a weekly podcast where Jen, Chris, and Matt unpack the science behind everyday health questions. No jargon, no judgment — just genuine curiosity and proper research.

    21 min

  5. Jun 4

    Why Do We Need Omega-3 and Are You Getting Enough?

    Your body cannot manufacture Omega-3. And yet roughly 40% of the brain's grey matter is built from it — making it one of the most important nutrients most of us consistently underestimate. In this episode, Jen, Chris, and Jamie unpack why Omega-3 is so much more than a vague health recommendation. They cover the critical difference between ALA and the active forms EPA and DHA, why plant sources alone aren't enough, and what a significant body of large scale research says about the effects on heart health, brain function, mood, joints, eye health, and pregnancy outcomes. They also address the omega-6 to Omega-3 ratio, the signs of deficiency that most people attribute to other causes, and how much EPA and DHA you actually need each day — versus what most people are actually getting. Timestamps 00:00 Introduction 01:00 The Building Block Your Body Can't Make 01:41 ALA, EPA and DHA — Not All Omega-3 Is Equal 03:39 Why Plant Sources Aren't Enough 04:30 Heart Health and Cardiovascular Evidence 05:38 Brain Function, Mood and Mental Health 07:16 Joints, Eye Health and Pregnancy 09:03 The Omega-6 to Omega-3 Ratio 10:07 Signs You're Not Getting Enough 11:25 How Much Do You Actually Need? 13:39 Finding the Right Source Key PointsWhy the source of your Omega-3 matters more than most people realiseOmega-3 is a family of fatty acids, not a single compound. The three main types are ALA, EPA, and DHA — and they are not interchangeable. ALA is found in plant foods like flaxseed and chia seeds. EPA and DHA are the active forms the body actually needs, found naturally in microalgae. Microalgae are the original producers of EPA and DHA in the food chain. Fish accumulate it by eating algae. As Jamie puts it: "The algae are doing all the work and the fish have been taking the credit this whole time." Your body can technically convert ALA into EPA and DHA, but the conversion rate is around 5% to EPA and well under 1% to DHA. Relying on plant foods alone for active Omega-3 isn't a realistic strategy. The cardiovascular and brain evidence is substantialA Cochrane review of 86 randomised controlled trials involving over 160,000 participants found that Omega-3 supplementation reduced triglyceride levels by around 15% and decreased rates of death from cardiovascular disease. The VITAL trial, which followed over 25,000 adults for more than five years, found that one gram of Omega-3 daily produced a 28% reduction in total heart attacks — rising to 40% for those who weren't already getting EPA and DHA through their diet. For the brain, DHA makes up a significant structural portion of grey matter. As Chris explains: "It firmly answers the question of whether a supplement this small can make a measurable difference to health." Deficiency signs are easy to missDry or irritated skin, joint stiffness without a clear injury, poor concentration, brain fog, mood changes, dry eyes, fatigue, and brittle hair and nails are all signs of low Omega-3. They're also the kinds of things most people put down to being tired or getting older. As Jen observes in the episode, people often spend time and money chasing individual solutions — a cream for dry skin, painkillers for joints, coffee for concentration — when part of the answer might be addressing one underlying nutritional gap. Most people are getting far less than they needMost health organisations recommend 250 to 500mg of combined EPA and DHA daily for healthy adults. The average person is currently getting around 100mg a day. Heavily processed fish products are unlikely to offer meaningful EPA or DHA unless fortified. The most reliable route is a quality EPA and DHA source — whether from oily fish or algae based supplements — taken consistently. As Chris puts it: "Consistency matters more than perfection. The best source is the one you'll actually take daily." About So That's WhySo That's Why is a weekly podcast where Jen, Chris, and the team unpack the science behind everyday health questions. No jargon, no judgment. Just genuine curiosity and proper research.

    16 min

  6. May 28

    Why Does Hair Turn Grey?

    Hair doesn't turn grey — every strand grows out of the follicle completely colourless. So when greying happens, what's actually failing is the system that was adding colour all along. In this episode, Jen, Chris, and Jamie unpack the biology of grey hair: the specialised cells that inject pigment into each strand as it grows, why those cells eventually stop working, and what a landmark study published in Nature revealed about stem cells getting physically stuck in the wrong part of the follicle. They also cover the hydrogen peroxide mechanism that bleaches hair from the inside, the Harvard research linking stress to accelerated greying, the genetic factors that set your personal timeline, and the nutritional deficiencies that are often overlooked as a cause of premature greying. And they ask the question most people quietly wonder about: can grey hair actually be reversed? Timestamps 00:00 - Introduction: why does hair turn grey? 01:03 - Hair grows grey, not turns grey 01:47 - Melanocytes: the cells that colour your hair 02:32 - The stem cell discovery that changed the picture 03:56 - Hydrogen peroxide: your body's internal bleach 05:07 - Stress, genetics and the pace of greying 07:11 - Nutritional deficiencies and premature greying 09:07 - Can grey hair actually be reversed? Key PointsYour Hair Was Never Actually Coloured to Begin With[01:03] Every strand of hair grows out of the follicle completely white. The colour you see is injected into the hair shaft during the growth process by specialised cells called melanocytes — and there are around 100,000 of them on the average head. Two types of pigment are at work: eumelanin (black and brown shades) and pheomelanin (blonde and red tones). Your unique combination of the two determines your natural colour. Greying isn't colour fading — it's the pigment system stopping. As Chris explains: "Every single strand of hair starts off completely white before pigment gets added. When we say our hair turns grey, what we actually mean is the pigment system has stopped doing its job." The Stem Cells Aren't Dead — They're Stuck[02:32] A study published in Nature revealed that melanocyte stem cells, the parent cells that produce new pigment-making melanocytes, normally shuttle between two compartments inside the hair follicle. In one they sit dormant; in another they receive the signals that tell them to mature and start producing colour. As hair ages through repeated growth cycles, those stem cells start getting physically stuck in the dormant compartment. They stop migrating to where the signals are and never receive the instruction to produce pigment. Jamie put it plainly: "It's like having all the ingredients for dinner sitting in the cupboard, but nobody's walking to the kitchen to actually start cooking." The significance is real — stuck cells are potentially fixable in a way that dead cells aren't. Your Body Is Bleaching Your Hair From the Inside[03:56] Hair follicles naturally produce small amounts of hydrogen peroxide as a byproduct of normal cell activity. An enzyme called catalase normally breaks it down into harmless water and oxygen — but catalase levels decline with age. When that happens, hydrogen peroxide builds up and interferes directly with pigment production. Researchers at the University of Bradford confirmed this by analysing pigmented hair versus grey hair: the grey samples contained high levels of hydrogen peroxide; the pigmented samples had none. The hydrogen peroxide also damages the repair mechanisms that would normally fix the problem, creating a compounding effect over time. Nutrition May Be Playing a Bigger Role Than You Think[07:11] For premature greying specifically, nutritional deficiencies are frequently overlooked. Vitamin B12 supports melanocyte function and deficiency is one of the most common nutritional causes of early greying — studies have found significantly lower B12 levels in people experiencing premature greying. Copper is another factor, acting as a co-factor for tyrosinase, the key enzyme in melanin production. Iron, zinc, vitamin D, and calcium have also been flagged in research. Addressing a deficiency may help slow further greying, though reversing existing grey hair through nutrition alone is uncommon. The primary benefit is in prevention, not reversal. About So That's WhySo That's Why is a weekly podcast where Jen, Chris, and the team unpack the science behind everyday health questions. No jargon, no judgment — just genuine curiosity and proper research.

    12 min

  7. May 21

    Why Does Blue Light Affect Sleep?

    We all know we shouldn't scroll before bed — but has anyone actually explained why blue light disrupts sleep? In this episode, Jen, Chris, and Matt unpack the biology behind one of modern life's most common habits. Specialised cells in your retina contain a protein called melanopsin that is maximally sensitive to blue light wavelengths — the same wavelengths emitted by our screens. When those cells fire, they signal your brain's master clock that it's daytime, suppressing melatonin and delaying your body's natural wind-down process. Your circadian system, it turns out, cannot distinguish your phone from the morning sun. The team also covers why children are significantly more vulnerable than adults, what the research actually says about blue light blocking glasses (the tint colour matters far more than most people realise), whether night mode on your phone is doing anything useful, and why the widely marketed claim that screens damage your eyes isn't supported by current evidence. Timestamps 00:00 - Introduction 01:37 - How much does blue light actually matter? 03:14 - The biology: what's happening in your brain 06:55 - Why children are more vulnerable than adults 09:45 - Do blue light blocking glasses work? 11:14 - Night mode, brightness and practical tips 13:04 - Does blue light actually damage your eyes? Your Phone Is Triggering a Sunrise Response[03:14] The reason blue light disrupts sleep isn't a vague sensitivity — it's a specific, hardwired biological pathway. Your retina contains specialised cells called IPRGCs (intrinsically photosensitive retinal ganglion cells) that contain a light-sensitive protein called melanopsin. Melanopsin is most sensitive to blue wavelengths between 460 and 480 nanometres, which overlaps directly with the light emitted by screens. When these cells detect blue light, they signal the suprachiasmatic nucleus — the brain's master clock — that it's daytime. The SCN responds by suppressing melatonin production in the pineal gland. As Chris explains: "Your circadian systems can't distinguish between natural daylight and artificial light from screens, because both activate the same pathway." The Numbers Are More Significant Than Most People Expect[01:37] Just two hours of evening screen use can suppress melatonin production by over 50% and delay the normal melatonin rise by an hour and a half. Around a third of people experience reduced sleep duration as a result, and half report feeling less tired at bedtime — which sounds convenient until you realise their natural drowsiness signals are being chemically overridden. The effects don't stop when you put the phone down, either. Melatonin suppression and the alerting effects persist for some time after the screen goes off. As Chris puts it, the circadian system doesn't have an instant reset button. Children Are Significantly More Vulnerable — Here's the Biology[06:55] A study comparing children (average age nine) to adults (average age 40) found that under blue light-enriched conditions, children experienced over 80% reduction in melatonin levels, compared to a much weaker response in adults. Two physical factors explain this. Children have larger pupils, which admit more light. Their eye lenses are also clearer — as we age, the lens naturally yellows, filtering out some blue light before it reaches the photosensitive cells. Children don't yet have that filter. As Matt observes: "The very thing that gives kids those beautiful crystal clear eyes also makes them more vulnerable to the screen." Blue Light Glasses and Night Mode: What the Research Actually Shows[09:45] Not all blue light glasses are equal. Clear lenses filter only 10 to 30% of blue light. Amber or orange lenses can block 90% or more — and studies involving people with insomnia found that amber-tinted lenses worn for two hours before bedtime did lead to measurable improvements in sleep quality and duration. Night mode alone isn't the full picture, either. A 2024 study found that overall screen brightness may matter as much as, or more than, colour temperature. Night mode combined with reduced brightness performs better than either setting alone. One important note: current evidence does not support the claim that blue light from screens damages eyes. The American Academy of Ophthalmology has stated there is insufficient evidence for this. The sun delivers up to 1,000 times more blue light than a screen. About So That's WhySo That's Why is a weekly podcast where Jen, Chris, and Matt unpack the science behind everyday health questions. No jargon, no judgment — just genuine curiosity and proper research.

    17 min

  8. May 14

    Why Do Your Muscles Get Sore After Exercise? (It's Not Lactic Acid)

    Lactic acid has been blamed for sore muscles for decades. The science says otherwise — and the real explanation is far more interesting. In this episode, Jen, Chris, and Matt unpack the truth behind delayed onset muscle soreness (DOMS): what's actually happening inside your muscle fibres, why the pain peaks a day or two after exercise rather than straight away, and why the familiar "no pain, no gain" mantra is more complicated than it sounds. Along the way they bust one of the most persistent myths in fitness, explain why running downhill causes more soreness than running uphill, and reveal which popular recovery methods are actually backed by evidence — and which aren't. (Stretching fans, brace yourselves.) In this episode: 00:58 — The lactic acid myth debunked02:21 — What's actually causing DOMS05:11 — Individual variation in soreness06:20 — The no pain, no gain myth07:43 — Should you exercise when sore?09:12 — What actually works for recovery The Lactic Acid Myth Has Been Comprehensively Disproven(00:58) For generations, "feel the burn, that's the lactic acid" has been repeated in gyms, by coaches, and in fitness articles. There's one straightforward problem with it: lactic acid clears from your bloodstream within 30 to 60 minutes of stopping exercise. DOMS doesn't even begin until 12 to 24 hours later. As Chris explains: "The lactic acid explanation has been comprehensively disproven. That timeline alone makes this theory impossible because muscle soreness typically doesn't begin until 12, even 24 hours post-exercise, sometimes longer." The culprit that fitness culture has blamed for generations couldn't physically be responsible. Your Body Has Builders In — And They Make a Lot of Noise(02:21) The real cause of DOMS is microscopic damage to muscle fibres and the surrounding connective tissue, followed by the inflammatory response your body launches to repair it. Specific hormones called prostaglandins and leukotrienes are released, causing swelling and activating pain receptors. The whole process takes time to develop — which is why soreness peaks one to three days after exercise, not immediately. Jen adds that DOMS may also involve damage to the deep fascia — the connective tissue wrapping around muscles — which is densely populated with pain-sensitive nerve endings. This explains why even gentle pressure on sore muscles can feel disproportionately uncomfortable. As Matt puts it: "The soreness is actually a repair job in progress. Like my body's got builders in. And they're making just an awful lot of noise." Getting Less Sore Over Time Is a Good Sign(06:20) One of the most widespread myths in fitness is that soreness equals an effective workout. Research conclusively demonstrates that DOMS is neither necessary nor sufficient for muscle growth. Some muscle groups, like the shoulders, rarely experience significant soreness yet still grow perfectly when trained properly. Chris explains the repeated bout effect: "Your body adapts to exercise through something called the repeated bout effect. That means you'll experience progressively less soreness for the same workout, even as your strength and muscle mass continues to increase." Getting less sore over time isn't a sign you're not working hard enough. It's a sign your body is adapting and improving. What Actually Works for Recovery (And What Doesn't)(09:12) An analysis of around 120 studies identified which recovery treatments have real evidence behind them: Active recovery — light movement at 30 to 60% of maximum heart rate — outperforms complete rest for reducing sorenessMassage therapy increases blood flow and may stimulate endorphin releaseCold water immersion at around 10 to 15 degrees Celsius shows effectiveness, as does contrast therapy (alternating hot and cold)Stretching reduces soreness by less than two millimetres on a 100-millimetre pain scale — effectively undetectable Beyond specific treatments, the fundamentals matter most: seven to nine hours of sleep (growth hormone released during deep sleep stimulates muscle repair), 20 to 40 grams of protein per meal, and increasing training volume by no more than 10% per week. About So That's WhySo That's Why is a weekly podcast where Jen, Chris, and Matt unpack the science behind everyday health questions. No jargon, no judgment — just genuine curiosity and proper research.

    15 min
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About

You've been told to drink eight glasses of water a day. You've chased 10,000 steps like it's some kind of biological law. You've checked your cholesterol without being entirely sure what you're actually checking for. Most health content tells you what to do. Nobody explains why. That's the gap So That's Why was made to fill. Each week, Jen, Chris, and Matt take one everyday health question — the kind that's been nagging at the back of your mind, or that you've just accepted without thinking — and unpack the actual science behind it. Where did this idea come from? What's really happening inside your body? And does the evidence actually hold up? What they find is often surprising. The 10,000-steps rule was invented by a Japanese marketing team in 1964. The eight-glasses-of-water recommendation came from a misread document. The reason some people turn tomato-red when they exercise has nothing to do with fitness — it's about blood vessel density. The thing that makes you cry when you chop onions was only properly understood in 2002. Cholesterol is in every single cell of your body — so why the terrible reputation? The science is real, the research is specific, and the conversations are genuinely fascinating. And the three people having them have the backgrounds to get it right. Jen holds a PhD in biochemistry and molecular biology. She asks the questions you're thinking — informed ones, not naive ones — and keeps the conversation grounded in the human experience of all this biology. Chris is a formulation scientist with over 30 years of experience. He's read the studies, knows the mechanisms, and has the analogies that make complex biology actually click. Matt looks at the science and asks what it means for real people, with real lives, real schedules, and no time for perfectionism. Together they hit that sweet spot between too technical to understand and so simplified it's not actually true anymore. Getting there, it turns out, is harder than it sounds. So That's Why doesn't give you a list of rules to follow. It doesn't shame you for the things you haven't been doing. It explains the mechanism — the actual biology — so you can make decisions that fit your life, rather than just following advice that might not apply to you at all. Episodes run about 20 minutes. They're built for commutes, workouts, or cooking dinner. By the end of each one, you'll be able to explain the answer to someone else — which is the whole point. New episodes every week. Subscribe and find out why.

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  • Creator
    Vegetology
  • Years Active
    2K
  • Episodes
    23
  • Rating
    Clean
  • Copyright
    © Copyright 2026 Vegetology
  • Show Website
    So That's Why

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