So That's Why

That strange tingling, buzzing sensation when your foot falls asleep is one of the most universal physical experiences there is. But almost everyone has it backwards: pins and needles don't happen while something is going wrong. They happen when things are being corrected. In this episode, Jen, Chris, and Matt unpack exactly what's happening at the nerve level when pins and needles strike. They co...

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 fascina...

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 theo...

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...

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 bus...

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 al...

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 publi...

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 cell...

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 ga...

Why does an unpronounceable ingredient feel more dangerous than arsenic — which is completely natural? In this episode, Jen, Chris, and Matt unpack the psychology and science behind food ingredient fear, from chemophobia and the Appeal to Nature Fallacy to the MSG panic that grew from a single doctor's letter. Along the way, they explain the dose-makes-the-poison principle, examine where seed oil...

You're completely full. And yet twenty minutes after dinner you're standing in front of the fridge, staring down a slice of cake. Sound familiar? Up to 97% of people experience food cravings — but almost nobody understands what's actually driving them. In this episode, Jen, Chris, and Matt unpack the brain science behind food cravings: why they're completely different from hunger, why chocolate to...

Nearly 90% of adults consume caffeine daily — yet most have no idea why it gradually loses its punch. If your morning coffee used to change your day and now just stops you feeling terrible, there is a biological reason for that. And it happens faster than you would expect. In this episode, Jen, Chris, and Jamie unpack the science of caffeine tolerance: what adenosine is and why it matters, how you...

Your body can make Vitamin D from sunlight — so why is nearly half the global population still deficient in it? In this episode of So That's Why, Jen, Chris, and Matt unpack what Vitamin D is actually doing inside the body, why the sunshine route fails so many people, and why deficiency shows up as fatigue, frequent illness, and muscle weakness rather than just weak bones. Along the way, they bust...

Cholesterol is in every single cell in your body — yet it's also called "the Silent Killer." In this episode, Jen, Chris and Matt unpack why the same molecule that keeps you alive can silently damage your arteries for decades before you feel a thing, and what you can actually do about it. In this episode: 00:00 — Introduction 01:02 — Why cholesterol has such a confusing reputation 02:09 — The scal...

That irritable, short-fused feeling when you've missed a meal has a name — and it turns out "hangry" is backed by serious science, not just a lack of willpower. In this episode, Jen and Chris are joined by Jamie for a deep dive into why hunger hijacks your mood. The team unpacks four separate biological mechanisms that fire simultaneously when blood sugar drops: stress hormones that can't be disti...

Why do onions make us cry every time we cut them — and why does cooking them make the problem disappear completely? About 70% of people experience significant tearing when cutting onions, and no matter how many you've chopped over the years, the reaction doesn't get easier. In this episode, Jen, Chris, and Matt unpack the full chemistry behind one of cooking's most universal frustrations. They exp...

Brain fog affects over a quarter of us — yet it isn't actually a medical diagnosis. So what's really happening inside your brain when thinking feels like wading through treacle? In this episode, Jen, Chris, and Matt unpack the real biological mechanisms behind brain fog — from neuroinflammation and a compromised blood-brain barrier to mitochondrial dysfunction and hormonal shifts. The team explain...

The ingredients on your supplement label that aren't the vitamin? They're not "fillers" and they're not there to cut corners. Most people don't know what these extra ingredients actually do, or why they're necessary. In this episode, Jen, Chris, and Matt tackle one of the most debated topics in the supplement world. With Chris's 30+ years as a formulation scientist, the team explains why supplemen...

Most of us have stood next to someone at the gym and wondered: why are they barely glistening while we look like we've run through a sprinkler? The answer is more fascinating than you'd expect — and it completely reframes what heavy sweating actually means. In this episode, Jen, Chris, and Matt unpack the biology behind sweat rate variation, from the hypothalamus acting as your body's built-in the...

Think going red during exercise means you're unfit? The science says otherwise. Exercise induced facial flushing has virtually no correlation with fitness level, and it might actually signal a more efficient cooling system. In this episode, Jen, Chris, and Matt explore why some people turn tomato red during a workout while others barely change colour. The answer lies in genetics, specifically in b...

Think you need to hit 10,000 steps every day? That target didn't come from a doctor or a clinical study. It came from a 1964 Japanese pedometer marketing campaign. In this episode, Jen, Chris, and Matt trace the surprising origin of the world's most famous fitness target and compare it with what modern research actually says about steps and health. A 2025 study published in The Lancet , analysing...

Less than 1% of the population genuinely needs less sleep. The rest of us claiming to be fine on four or five hours? We're most likely accumulating something called sleep debt, and our brains have become numb to the damage. In this episode, Jen, Chris, and Matt unpack the genetics of natural short sleepers, what your brain actually does while you're asleep, and why "adapting" to less sleep is one...

The "eight glasses of water a day" rule has been repeated so often it feels like biological law. But what if the whole thing started with a misunderstanding? In this episode, Jen, Chris, and Matt trace the eight-glasses myth back to a 1945 report that almost everyone misread, examine a landmark study of 5,600 people across 23 countries that revealed individual hydration needs can vary by up to 1,0...

Health advice is everywhere — but almost nobody explains why. Meet the team changing that. In this launch episode of So That's Why, hosts Jen, Chris, and Matt introduce the podcast that takes everyday health questions and actually answers them — with real research, proper context, and the kind of curiosity that makes you want to tell someone about it afterwards. The team behind Vegetology — a scie...