SUNLIGHT, SWEAT AND SEROTONIN: HOW TO WARD OFF A SEASONAL SLUMP

As we bask in glorious summer sun, most of us enjoy a serotonin boost that lifts our mood. However, when the days shorten and the skies darken, many people experience a dip in mood and energy. For some, this seasonal slump deepens into Seasonal Affective Disorder (SAD), a form of depression that recurs annually during the fall and winter months.

While light therapy and mindfulness practices have long been recommended, new research highlights a powerful natural ally in the fight against seasonal sadness: exercise – specifically the unique effect it has on vitamin D levels.

The virtues of Vitamin D
Vitamin D is credited with the production of feel-good neurotransmitters like serotonin and dopamine. Those who are depressed commonly have low vitamin D levels and vitamin D deficiency is shown to exacerbate SAD. However, researchers have found that supplementation of vitamin D does not directly improve symptoms. And in places where winters are particularly long and dark, simply getting outside for a natural sunshine-induced vitamin D hit isn’t really an option.

This is where exercise comes in…

A fascinating 2025 study from the University of Bath found that regular, moderate-intensity exercise can actually preserve vitamin D levels during winter, even without sunlight or supplements. Participants in the study who followed a 10-week indoor exercise program experienced a smaller drop in their overall vitamin D levels over winter – about 15%, compared to a 25% drop in those who didn't exercise. More importantly, exercise helped maintain levels of the active form of vitamin D (1,25(OH)₂D₃) – this is what supports immune function, bone health, and mood regulation

Those who exercised saw a smaller drop in their overall vitamin D levels over winter – about 15%, compared to a 25% drop in those who didn't exercise.

The exercise advantage
Physical activity is a well-regarded mental health booster, and a well-balanced workout routine is shown to reduce poor mental health days by almost 50%. Now, with this new discovery, we can see exercise doesn’t just boost mood through endorphins – it also helps sustain the biochemical foundation for mental health by preserving vitamin D levels when sunlight is scarce.

Exercise reduces poor mental health days by almost 50%.

Practical tips for year-round wellness

• Move regularly: Aim for at least 3 to 4 sessions of moderate-intensity exercise per week
• Mix it up: Combine cardio and strength training with mindfulness-based activities like yoga or guided meditation.
• Get outside when possible: Even limited sunlight can help, and time in nature has its own mood-boosting effects.

Remember, exercise is more than a tool for physical fitness – it’s a vital strategy for maintaining mental health and biochemical balance. By staying active, you’re not just lifting weights – you’re lifting your mood, your immunity, and your vitamin D levels.
 

Article by Emma Hogan Supplied By Les Mills International