Understanding your body's seasonal shifts

Feeing sluggish, low energy, or just a bit ‘off’? You’re not alone, and you’re not imagining it!

As the days grow shorter and the air turns crisp, you might notice yourself feeling heavier, more tired, or slower to bounce back from everyday stress. Maybe your motivation dips, your mood feels flatter, or small aches linger longer than usual. It’s easy to blame the “winter blues” or a lack of sunshine—but what if your body is actually responding in a very real, biological way? Research shows that winter doesn’t just change the weather; it changes your internal biology. Your immune system, hormonal responses, and even the activity of thousands of genes shift with the seasons. Understanding these seasonal rhythms can help you work with your biology, not against it.

Your body responds to the seasons

Scientists have discovered that the immune system is not static year round, it shifts in predictable patterns as seasons change.

One large study looked at gene activity across the immune system, with researchers finding that 23% of protein coding genes showed differences in expression, with distinct patterns for winter and summer months. Meaning thousands of genes involved in immunity are essentially “tuned” by the season.¹

What’s really interesting is that the immune pathways more active in winter are largely pro-inflammatory. This helps explain why conditions like cardiovascular issues and autoimmune flares tend to spike in winter—the body’s internal gene expression landscape is different. This isn’t just one small group of people either, these seasonal gene expression patterns have been observed in diverse populations from both northern and southern hemispheres, suggesting this is a feature of human biology rather than a lifestyle effect.²

How winter shapes immunity, mood and energy

Winter doesn’t just change how we feel emotionally, it changes how our bodies function at a cellular level. The immune system, nervous system and brain are constantly communicating and seasonal shifts affect all three at once.

Large population studies show that key immune biomarkers, including white blood cell count and inflammatory markers such as C-reactive protein, follow clear seasonal patterns. Winter months are associated with a more pro-inflammatory profile, and these shifts occur even when lifestyle factors are accounted for, suggesting that our bodies are responding to seasonal cues rather than behaviour alone.³

At the same time, research into seasonal biology shows that thousands of genes involved in immune function, metabolism and brain signalling change their expression depending on the time of year. In winter, gene activity favours heightened immune vigilance—a useful adaptation for cold months—but this can place extra strain on the body if combined with chronic stress or poor recovery.⁴

These biological shifts help explain why many people notice changes in mood, motivation, and energy as days grow shorter and colder. Studies on seasonal patterns in mental health suggest these changes aren’t just psychological—they are physiologically driven, influenced by light exposure, circadian timing, and immune signalling. Even outside of diagnosed seasonal affective disorder (SAD), subtle winter-related dips in mood and vitality are common.⁵

What we often label as “low energy” or “winter blues” may actually be the body responding intelligently to seasonal conditions. It may be asking for more rest, slower pacing and better regulation—exactly what our internal systems require during this time.

Working with your body’s seasonal rhythm

Winter biology is designed for containment, not expansion—for maintenance and protection, rather than constant growth. Here’s how to support your body during these months:

Prioritise depth over volume – Focus on fewer tasks done more slowly. This helps regulate your nervous system and conserve energy that would otherwise be spent managing overload.

Reduce urgency – Urgency signals threat to your nervous system, so slowing down transitions, leaving buffer time and doing things more slowly with presence can help keep your body out of chronic stress activation.

Build rest into your day – Short pauses, warmth, silence and moments without stimulation all count as rest. These micro-rests support your immune regulation and prevent stress from accumulating unnoticed.

Listen to your body’s signals – Emotional flatness, persistent tiredness, frequent minor illnesses and feeling wired but depleted are often early signs of overload; signals that your body needs support rather than more effort.

Winter is not a problem to be solved, but a season the body responds to in real and measurable ways. Shifts in immunity, inflammation and energy are all part of an adaptive rhythm. When you slow down in winter, you’re not giving up momentum; you’re supporting your body while it works differently. Slowing down, reducing urgency, and pacing yourself gently allows these processes to unfold naturally, laying steadier foundations for the months ahead.

For more ways to stay well this winter check out 3 non-negotiables for staying well this winter & Seasonal affective disorder (SAD): 9 tips for reclaiming your mood this season!

Any questions? Contact one of our Nutritional Therapists via live chat, weekdays from 8 am to 8 pm.

“Winter blues” or biology? Understanding your body’s seasonal shifts

Your body responds to the seasons

How winter shapes immunity, mood and energy

Working with your body’s seasonal rhythm

References

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