Here’s what we’ll cover in this blog post:
- What the “winter exposome” is and why it matters for longevity
- How winter affects circadian rhythms, light exposure, and mitochondrial function
- The role of air quality, movement, and nutrition in energy production
- Why seasonal infections and mood shifts disrupt cellular health
- Simple strategies to support mitochondria during colder months
With winter comes a change in the weather and in our biology.
You can think of your winter exposome as the total package of exposures your biology experiences between roughly November and March: light, temperature, air quality, infections, dietary changes, alcohol consumption, movement patterns, social context, and stress.
Circadian Rhythm Disruption and Light Deficit
As days shorten, your internal clocks start to drift.
Every cell in your body has a circadian rhythm: 24-hour cycles that regulate gene expression, hormone release, metabolism, and repair. These are synchronized by light, especially bright, blue-enriched morning light.
In winter:
- There’s less morning light and more prolonged darkness.
- We spend more time indoors under dim, unnatural lighting.
- UVB exposure falls, dropping vitamin D production.
- The long, early dark period can drive melatonin production earlier and for longer.
When those clocks fall out of sync, a few things tend to happen:
- Sleep becomes lighter, fragmented, or irregular.
- Insulin sensitivity drops; blood sugar control worsens (many don’t realize that sunlight is a powerful regulator of insulin sensitivity).
- Inflammatory pathways become more active.
Mitochondrial genes that follow circadian rhythms (like those involved in biogenesis and cellular energy production) become dysregulated.
In the brain, disrupted circadian rhythms plus low light exposure increase risk for seasonal affective disorder (SAD) and mood changes. We also see mitochondrial differences in mood disorders (e.g. depression) including altered behavior, reduced cellular energy production, impaired repair and maintenance. Winter can amplify those underlying vulnerabilities.
Cold Stress: Thermogenesis and ROS
Cold temperatures aren’t just uncomfortable; they’re metabolically expensive.
When we’re exposed to cold, our body increases thermogenesis, heat production, in brown adipose (fat) tissue and muscle. That requires:
- Increased mitochondrial activity (mitochondria burn fuels to generate heat for us).
- More ROS generation.
Cold exposure makes our mitochondria work harder, and “pollution” inside the cell (reactive byproducts) rises.
Short, controlled doses of cold exposure can activate mitohormesis to:
- Increase mitochondrial production in (brown) fat.
- Improve clearance of blood sugar.
- Enhance metabolic activity and ability to burn fuels in muscle.
But the key distinction is brief, intentional exposure versus passive, chronic exposure to the cold.
Air Pollution and Indoor Air Quality
In many regions, winter air quality gets worse, not better.
- In the winter, pollutants get trapped closer to the ground (a process called inversion)
- We seal up buildings, increasing indoor CO₂, volatile organic compounds (VOCs), and particulate matter from cooking and heating.
- Wood stoves, gas heaters, and even candles add toxic particulate matter to the air.
Air pollutants like PM2.5 and nitric oxide are potent mitochondrial stressors. They:
- Damage mitochondrial DNA.
- Decrease cellular energy production.
- Increase ROS and impair mitochondrial quality control.
On a day-to-day basis, that can mean fatigue, headaches, reduced exercise tolerance, worsened asthma, or COPD. Long-term, chronic exposure contributes to cardiovascular disease, neurodegeneration, and shortened lifespan, much of it is thought to be mediated by mitochondrial damage and dysfunction.
Metabolic Drift, Holiday Eating, and Alcohol
Winter eating patterns are often the biological equivalent of leaning on the gas pedal while the engine is already overheating.
From an evolutionary standpoint, it makes sense: colder temperatures and shorter days historically signaled possible scarcity ahead. Our bodies are wired to:
- Increase appetite.
- Prefer calorie-dense, high-fat, high-carb foods.
- Store more energy as fat.
Modern life has turned our biology against us: we get the evolutionary drive to overconsume, but there’s no true scarcity. Instead, there’s celebration, more time indoors with abundant access to sugar, refined carbs, processed snacks, and alcohol.
Chronic overnutrition:
- Overloads mitochondria with fuel.
- Increases ROS and damage to lipids (key fats that are part of our cellular membranes), and is used to make hormones like estrogen and testosterone.
- Drives insulin resistance and visceral fat accumulation in the liver, muscle, and around the abdomen.
Post-meal, people feel this as crashes: fatigue, irritability, and sleepiness. Repeating this vicious seasonal cycle over years drives the progression of type 2 diabetes, fatty liver, cardiovascular disease, and cognitive decline, all conditions with a strong mitochondrial component.
Overconsumption of alcohol during the holiday seasons slathers on another layer of stress. Ethanol is a mitochondrial toxin:
- It increases ROS production.
- Damages mitochondrial DNA and respiratory chain proteins.
- Impairs ATP generation.
- Can induce apoptosis (cell death) at high doses.
Viral Infections and Immune Load
Winter is also an infection season. Viruses like influenza, respiratory viruses, and various coronaviruses circulate more in colder months. That creates two overlapping stressors:
- Immune activation – which is energy-intensive and pro-inflammatory.
- Direct viral effects on mitochondria – many viruses target mitochondrial pathways (basically hijack mitochondria) to evade immune responses.
Repeated infections, incomplete recovery, and chronic low-grade inflammation:
- Add cumulative mitochondrial damage.
- Drive immunosenescence (immune cells accumulate damage, experience impaired function, and shift toward a pro-inflammatory phenotype).
- Fuel inflammaging and increased frailty over time.
Stress Load, Mood Shifts, and Neural Energy Demand
Finally, winter changes how we live.
- Back-to-school and year-end work deadlines.
- Holiday obligations and financial stress.
- Less time outside, less nature, less unstructured social connection.
Chronic psychological stress elevates cortisol and sympathetic nervous system activity. Over time, that:
- Increases mitochondrial reactive oxygen species.
- Alters mitochondrial function and repair.
- Impairs sleep and recovery.
- Changes how brain circuits involved in mood and motivation function.
Neurons are especially energy-hungry. They rely heavily on efficient mitochondrial ATP production and precise calcium handling. When stress is high and recovery is poor, you see the familiar winter pattern: low mood, reduced motivation, impaired focus, and less drive to move, all of which feed back into more mitochondrial dysfunction.
Bottom Line
Winter affects nearly every system in the body. At the center of those effects are the mitochondria—the powerhouses of the cell.
Supporting them starts with simple habits:
- Get outside in the morning for light exposure.
- Move daily, even if indoors.
- Eat nutrient-dense foods and limit alcohol.
- Use an air purifier when indoors for long periods.
- Consider targeted supplementation with treatments like NAD+ and Glutathione to fill winter gaps.
Your mitochondria don’t need perfection, just protection. Small steps now can help preserve your energy, metabolism, and cellular health through the season and beyond.
Note: The above statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.