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How to beat Winter Depression with Neuroscience

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Hello Reader,

I broke the cycle of winter depression.

Like so many, I find my overall energy levels gradually dwindling as days get shorter. At the latitude of England (where I live), days can get as short as just below 8 hours during the winter solstice.

Little sunlight. Freezing temperatures. Life becomes a little grim.

This phenomenon has a name: Seasonal Affective Disorder, which (quite fittingly) goes by the acronym SAD. It is officially recognized as a form of seasonal depression. The condition is truly seasonal: I feel perfectly fine most of the year, and when I escape to warmer climates, my mood lifts immediately. There's no doubt it's linked to the changing seasons. And I am not alone: About 1 in 3 people in the UK experience this “winter depression”. Oftentimes without being fully aware of it.
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The good news?
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Understanding the brain science behind SAD empowers us to fight its symptoms. And no, you won't need to book a flight to Southern Italy.
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Let me explain.

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How Shorter Days Impact Your Brain

As darkness sets in earlier each day, your brain undergoes subtle but significant changes.

Your circadian rhythm is the internal clock regulating your sleep-wake cycle. It relies on natural light cues. Shorter days disrupt this rhythm, making it harder for your brain to maintain its usual balance. As daylight fades, levels of serotonin (which stabilises mood) drop. In the meantime, melatonin (which induces sleep) rises. This occurs because natural sunlight normally suppresses melatonin production in the pineal gland. Therefore, during dark winter hours, melatonin production increases.

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According to the Phase Shift Hypothesis (PSH) it is this misalignment between the environment and our body’s circadian rhythm that causes SAD.

In particular, your brain’s hypothalamus struggles to manage these changes. Sleep patterns shift, and you may oversleep but still feel exhausted. Cravings for carbohydrates increase as your brain seeks quick sources of energy. Neurotransmitter imbalances make it difficult to maintain motivation or focus. These shifts affect mood, energy, and overall mental well-being.

Vitamin D deficiency often worsens these effects, as sunlight is essential for producing this nutrient. Low vitamin D levels can further reduce serotonin activity, amplifying depressive symptoms.

But there is hope.

How to Combat SAD

There are effective ways to feel less SAD during winter.

While there is no magic cure, these methods have been shown to relieve symptoms in a plethora of populations:

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Light Therapy

Using a specially designed light (emitting at least 10,000 lux) for 20-30 minutes in the morning can mimic natural sunlight, boost serotonin levels, reduce melatonin levels and improve mood. And believe me, regular desk lamps won’t work—you'll need specially designed light therapy lamps that are clinically proven to treat SAD.

I personally recommend this light by Lumie—it has worked wonders for me. At 10,000 lux when placed nearby, it provides bright light without being overwhelming. I keep it next to my laptop while working for about 30 minutes each day. Check it out here.

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Vitamin D Supplements

If you have low vitamin D levels, supplements can help alleviate symptoms. And you probably do, as 50% of the world’s population has insufficient vitamin D levels.

However, more is not always better.

Unlike vitamin C, which is water-soluble and easily excreted through urine, vitamin D is fat-soluble and can accumulate in the body, potentially leading to hypercalcemia (high calcium levels). Most sources such as the European Food Safety Authority (EFSA) consider 4,000 IU to be the safe limit for daily doses in adults.

For most adults, a daily dose of 600-800 IU is enough. However, people with darker skin may need to take higher dosages (1,000-2,000 IU) as their Vitamin D production is generally lower. Unfortunately, a lot of supplements you will find online have alarmingly high dosages. These, for example, will do just fine.

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Sun Exposure

Spend time outdoors during daylight hours. Arrange your workspace near windows to maximise natural light. Even short walks outside can stabilise your internal clock. Walks in nature can be especially beneficial for our mental well-being, as we have established already.

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Healthy Habits

Prioritise regular exercise, a balanced diet, and consistent sleep patterns. Stay socially connected through volunteering, group activities, or spending time with loved ones. Not rocket science, am I right?

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Take Home Points

• Understand Circadian Rhythm Disruption: Shorter days misalign your body's internal clock, impacting mood, energy, and sleep patterns. Prioritize strategies to stabilize your circadian rhythm.
• Leverage Light Therapy: Use a clinically approved lightbox (10,000 lux) for 20-30 minutes each morning to mimic sunlight and improve serotonin levels.
• Supplement with Vitamin D: If deficient, vitamin D daily to support mood and energy, but avoid excessive doses to prevent health risks.
• Adopt Healthy Winter Habits: Spend time outdoors, exercise regularly, and maintain social connections to combat the effects of Seasonal Affective Disorder.
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Understanding the neurobiological causes of SAD enables us to combat its symptoms through effective strategies like light therapy, vitamin D supplementation, and healthy habits—helping you maintain mental wellbeing throughout winter.

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