The Seasonal Brain: How Light, Neurodivergence and Circadian Biology Shape Our Mood

by Nik Ramsay-Trease and Anne Davis

Every year, as summer slips into autumn, many of us feel an emotional shift. A favourite Poet, Keats, captured it beautifully — “Season of mists and mellow fruitfulness” — and plenty of musicians from Marianne Faithfull to Green Day have echoed the same sense of transition. For some of us, the end of summer brings relief from an overstimulated nervous system; for others, a low mood or creeping heaviness that simply doesn't seem to have an explanation.

At Rewired Brain, we often hear clients talk about this end of summer transition and the impact it has on their wellbeing, resilience and sense of balance. Our brains and bodies are constantly responding to changes in our environment, and the move from summer to autumn can be more significant than we anticipate and make a real impact in our day to day lives.

A neurodivergent colleague once proudly declared, “I am a winter person.” which is a perfect description of being at peace with her own sense of self. For her, the sensory intensity of summer — heat, glare, brightness — was overwhelming. Winter felt calmer, quieter, more predictable.

This raises an intriguing question: do our brains have a favourite season?

Neuroscientists, psychologists and even ancient philosophers have explored this idea. Early civilisations worshipped the sun; modern Druids still gather at Stonehenge for the solstice. Our relationship with light is not just cultural — it is biological.

The Brain’s Relationship with Light

For those of you that have attended one of our workshops, you will be familiar with how we teach that the circadian rhythm is one of the most powerful regulators of human physiology. It influences not just our sleep, but our hormones, emotional regulation and our cognitive performance.

In our brains, a tiny cluster of cells called the suprachiasmatic nucleus (SCN) acts as the body's internal timekeeper. It sits deep within the hypothalamus and takes its cues directly from the light entering our eyes. As the days become shorter and darker, the SCN helps reset our internal rhythms, influencing everything from sleep and energy levels to mood, focus and hormone production. In other words, seasonal changes don't just happen around us, they create real biological changes within us too.

As we experience reduced daylight in winter, it can lead to:

• decreased serotonin activity (our neurotransmitter that regulates mood)

• increased melatonin production (preparing our bodies for rest)

• disrupted sleep–wake cycles

• changes in dopamine signalling (our sense of motivation and reward)

• shifts in energy, appetite and motivation

These changes affect everyone to some degree, but for neurodivergent individuals, the impact can be even more pronounced.

Neurodivergence and Seasonal Sensitivity

Many neurodivergent people tell us they notice the changing seasons more than other people seem to. That's not surprising when you consider how closely our brains are connected to light, sleep, routine and sensory experiences.

Research suggests that people with ADHD may be more vulnerable to seasonal and circadian rhythm disruptions, which can affect mood, energy levels, motivation and overall wellbeing. But this doesn't mean everyone with ADHD will experience Seasonal Affective Disorder (SAD). Rather, it highlights how seasonal changes can interact with an already sensitive nervous system.

If you're someone who finds yourself feeling more tired, less motivated, more emotionally reactive or simply "not quite yourself" as the seasons change, there may be a biological reason for that.

Some research also suggests that women can be more affected by seasonal changes than men. So, if you're a woman with an ADHD neurotype, understanding the relationship between your brain, your hormones and the changing seasons can be particularly helpful. Sometimes what feels like a personal failing is actually your nervous system responding to shifts in the environment around you

When Seasonal Changes Affect Mental Health

Seasonal Affective Disorder (SAD) however, is much more than simply feeling fed up with the darker days. It is a recognised form of depression that is linked to reduced exposure to natural light and the effect this has on the brain and body.

For many people, this might show up as persistent low mood, increased fatigue, sleeping more than usual, finding less enjoyment in activities, struggling to focus, feeling irritable or noticing changes in appetite. For some, these symptoms can become severe and have a significant impact on day-to-day life.

At Rewired Brain, we often remind clients that these experiences are not a sign of weakness or a lack of resilience. They are the result of very real biological changes occurring within the nervous system. Understanding what is happening in the brain can be an important first step towards responding with compassion, support and practical strategies that help us navigate the darker months more effectively.

Why Some Brains Prefer Winter

Not everyone experiences the seasons in the same way. Whilst some people thrive in the energy and brightness of summer, others find it overwhelming.

For many neurodivergent people, summer can bring sensory challenges. Brighter light, hotter temperatures, busier environments and disrupted routines can leave the nervous system working overtime. It's not unusual to feel more drained, irritable or overwhelmed during these months.

Winter, on the other hand, often offers something different. Softer light, quieter days, cooler temperatures and more predictable routines can feel calming and regulating. Many of the neurodivergent clients we work with describe feeling more focused, creative and settled as autumn and winter arrive.

This may help explain why some people genuinely look forward to the darker months. It's not necessarily about liking the cold or the rain. Sometimes it's simply the relief of a nervous system that no longer has to work quite so hard.

What Nordic Countries Teach Us About Seasonal Mindset

In Nordic countries, where winters are long and dark, there is often a different attitude towards the season. Rather than viewing winter as something to endure, it's seen as a time for slowing down, connecting with others and embracing simple comforts.

Concepts such as hygge, koselig and mysig all centre on creating warmth, comfort and a sense of wellbeing during the darker months. There's something we can learn from that. Instead of fighting the season, we can focus on supporting our nervous systems by creating environments that feel safe, calming and restorative.

So How Can You Support The Seasonal Brain?

1. Get More Morning Light

One of the most effective ways to support your brain through the darker months is to increase your exposure to light, especially first thing in the morning. For some people, a 10,000-lux light box can be helpful in resetting the body's internal clock, improving energy levels and lifting mood. Think of it as giving your brain the daylight cues it may be missing.

2. Create a Nervous-System-Friendly Environment

As the seasons change, many people benefit from making their environment feel a little more supportive. Warm lighting, comforting textures, predictable routines and opportunities for quiet downtime can all help regulate the nervous system. This is particularly important for people who are sensitive to sensory overload or whose energy levels fluctuate with the seasons.

3. Don't Underestimate Daylight

Even on grey days, getting outside can make a difference. A short walk, a coffee in the garden or simply stepping outside for a few minutes of natural light can help support your circadian rhythms, improve alertness and boost mood. It isn't about perfect weather. It's about giving your brain the light signals it needs.

4. Keep Moving, Even Gently

Movement doesn't have to mean intense exercise. A walk, some stretching, dancing around the kitchen or a swim can all help. Physical activity supports the release of serotonin and dopamine, chemicals that play an important role in mood, motivation, focus and emotional wellbeing.

5. Reach Out for Support

Sometimes the most helpful thing we can do is talk things through. Therapy and coaching can provide space to understand what's happening, develop practical coping strategies and navigate seasonal challenges with greater self-compassion. Rather than fighting the season, it can help to explore how we might work with it, embracing opportunities for rest, reflection and growth.

Closing thoughts..

Keats described autumn as a season of "mists and mellow fruitfulness" and perhaps he captured brilliantly something many of us still recognise today. As the seasons change, so do we.

Our brains are constantly responding to the world around us. Changes in daylight, temperature, routine and sensory input all influence how we feel, think, sleep and function. Sometimes those changes are subtle. Sometimes they are impossible to ignore.

Some people come alive in the long, bright days of summer. Others find themselves breathing a little easier when autumn arrives and life feels quieter, cooler and less overwhelming. Neither experience is right or wrong. It's simply the way our individual nervous systems interact with the world around us.

For neurodivergent people in particular, seasonal changes can have a real impact on energy, focus, emotional regulation and overall wellbeing. Understanding that can be incredibly validating. What looks like a lack of motivation or resilience is often a brain and body responding exactly as they are designed to do.

So as we move into the darker months, perhaps the question isn't how we push through them, but how we listen to what our nervous system needs.

More light. More rest. More movement. More connection. More self-compassion.

Because the goal isn't to fight the seasons. It's to understand how your brain experiences them, and learn how to work with that, rather than against it.

References

Wynchank, D.S., Bijlenga, D., Lamers, F., Bron, T.I., Winthorst, W.H., Vogel, S.W., Penninx, B.W., Beekman, A.T.F. and Kooij, J.S. (2016), ADHD, circadian rhythms and seasonality. Journal of Psychiatric Research, 81, pp.87-94. https://doi.org/10.1016/j.jpsychires.2016.06.018.

Luu, B. and Fabiano, N. (2025). ADHD as a circadian rhythm disorder: evidence and implications for chronotherapy. Frontiers in Psychiatry, 16, Article 1697900. Available at: Frontiers in Psychiatry (Accessed: 20 September 2026).