Seasonal Immunity: Preparing Your Body for Autumn’s Challenges
Originally sent on 28 September 2025
The leaves are falling, the light is fading, and so is our immune resilience. Every autumn I see the same pattern: coughs, colds and sore throats creeping in. It hit close to home last week when my little dog Stormzy spent four days in hospital with a fever. Watching him, withdrawn, no appetite, no wagging tail, reminded me how universal this is. And here’s what's important: it’s not the virus that decides the outcome, it’s the host. Your immune system is the deciding factor. Let’s dive in…
DATA — Where insight becomes impact
What I’ve been looking at this week…
Here’s a quick overview of your immune system. It’s made up of two complementary forces:
Innate immunity — this is your rapid-response team: T‑cells, macrophages, natural killer cells, complement proteins and cytokines like IL‑6. They act quickly and broadly.
Adaptive immunity — this is your precision team: antibodies like IgG and memory T‑cells. They remember past invaders and respond with accuracy.
Because immune cells are stationed at every barrier — gut, lungs, skin — your microbiome is critical. The microbes living inside and on you constantly train immune cells to tell the difference between harmless and harmful.
So why do autumn and winter bring more infections? Here’s what’s striking: the answer isn’t just “more viruses.” It’s also that your immune system is weaker when the days are shorter.
How the seasonal immune clock works:
As daylight shortens in autumn, your pineal gland produces more melatonin. Most people know melatonin as the hormone that helps you fall asleep, which it does, but it’s also a seasonal signal, telling your brain that the environment is shifting.
That signal is processed by the hypothalamus, the master regulator of your body’s rhythms: sleep, hunger, temperature, reproduction and immunity.
From there, the hypothalamus communicates with the thyroid gland, which sets your metabolic tempo and influences how immune cells are produced and deployed. Too little thyroid drive, and immune responses slow. Too much, and they overshoot.
This light–melatonin–hypothalamus–thyroid circuit creates your seasonal immune clock. A landmark UK Biobank study of more than 329 000 people confirmed this with hard data: immune cell numbers and inflammatory markers rise and fall with both time of day and day length. Which means that just as more viruses start circulating in autumn, your defences become seasonally weaker. As autumn light fades, your baseline protection automatically dials down — which means it’s even more important for you to actively dial it up.
DEVICES — Track it to hack it
What I’ve been monitoring this week…
Here are three essential devices to use at home so you can detect and respond early to viruses this season:
Thermometer: The classic tool, but with controversy. For decades, mercury thermometers were the gold standard — accurate, reliable, but risky because mercury is toxic. Today’s best options are:
Digital oral thermometers: safe, fast, precise. Can also be used under the arm for an axillary reading (and can be used in dogs rectally — though I would definitely advise against sharing the same thermometer with your dog!).
In‑ear thermometers: great for children, but angle matters.
Forehead/infrared thermometers: quick and touch‑free, less precise.
Heart rate monitor: Your heart rate often rises before your temperature does — a phenomenon called tachycardia. One of the earliest infection signs is a resting heart rate jumping 10+ beats above your baseline. Wearables like Oura, Apple Watch, Garmin and Whoop detect this. That means if you’re someone who tends to push through, tracking your heart rate can stop you before your body crashes.
Red‑light device: Viruses increase energy demand and can drain your mitochondria, which explains why catching a virus can feel like you’ve been hit by a bus. Red and near‑infrared light recharge mitochondria to produce more ATP, your energy molecule. A 10‑minute evening red‑light session can shift fatigue and inflammation, supporting faster bounce‑back. Together, these three devices give you foresight, feedback and fuel.
DECISIONS — From knowing to doing
What this means for you…
Here’s your I.M.M.U.N.E. playbook for autumn resilience:
I – Inhale: Short bursts of fast, deep breathing followed by breath holds raise adrenaline. Adrenaline mobilises immune cells and sharpens their innate response, which means your system is primed before you’re exposed. Breathe in through your nose and out through your mouth rapidly 30 times then on the exhale hold your breath for as long as you can. Repeat three times.
M – Microbiome: Around 70 % of your immune system sits in your gut lining. Feed it with ferments like kefir or sauerkraut, fibres like leeks and garlic, and polyphenols like berries and green tea. This means your gut microbes keep training your immune system to stay responsive.
M – Mobilise: Regular movement keeps immune cells circulating through blood and lymph. Just a short walk or stretch every hour ensures immune surveillance is active, which means cells are where they need to be when an invader appears.
U – Unplug: Melatonin doesn’t only help you sleep — it directs immune timing. Follow the 8‑80 rule: 80 minutes screen‑free before eight hours of sleep. Raising melatonin means your immune rhythms stay in sync.
N – Nourishments: Every immune response is a cycle of activate, attack, resolve. Three nutrients anchor that cycle:
Vitamin D: the “on switch” for immune cells. Low levels make the whole response sluggish. Food sources: oily fish (salmon, mackerel, sardines), egg yolks, fortified dairy and plant milks.
Zinc: essential for T‑cell development and function. Without it, your frontline cells can’t mature properly. Food sources: pumpkin seeds, oysters, crab, beef, chickpeas.
Omega‑3 fatty acids: help resolve inflammation once the infection is controlled, which means faster recovery without lingering fatigue. Food sources: salmon, sardines, mackerel, anchovies, walnuts, flaxseeds.
E – Environment: It’s a beautiful time of year to be outside. The autumn colours, the crisp air, the blue skies. Get outside daily. Fresh air reduces viral concentration compared to indoor air, which means your exposures are lower and your rhythms sharper.
Case in point:
One of my clients came to see me in early September last year. Every autumn he followed the same pattern: infections that would knock him out for weeks, disrupting travel, delaying projects and draining his energy just when the business year was at its busiest. We ran nutrient testing and discovered low omega‑3 and zinc. We corrected those, strengthened his gut microbiome and fine‑tuned his sleep routine. As a result, for the first time in years he went through autumn and winter without a single infection — even while flying internationally. Acting early is what makes the difference.
DIARY — Where you’ll find me…
Last week: I was speaking with several family offices on aligning health and wealth strategies. These are clients who understand that health preservation is wealth preservation, and that protecting longevity is as important as protecting legacy.
This week: I’m on stage at Pause Live, speaking about sleep, midlife energy and immune rhythm. For many women in this life stage, regaining health is the lever that unlocks leadership. It ties in beautifully with my client work. One client recently doubled her deep sleep time after we personalised her evening routine based on testing and tracking. That kind of transformation is exactly what I’ll be sharing with the audience: how data‑driven strategies can change both nights and days.
Next week: I’ll be in Birmingham, leading my workshop “The Entrepreneur’s Edge: Biohacks for Business Brilliance.” I always enjoy these close‑knit sessions; they’re a chance to work closely with entrepreneurs who want their health to match the pace of their ambitions.
DISTINCTION — A thought to pause on…
“The true test of immunity isn’t avoiding infection; it’s how quickly you respond and recover.” Which means your focus this autumn should be on preparation, so your system rebounds faster and stronger every time.