Vitamin D and Shorter Days: Staying Energized in the Darker Months

Nov 30

ESTIMATED READ TIME: 12 minutes

Have you noticed that when the daylight gets shorter, the weather gets colder, and you spend more time indoors, your energy, motivation, and even mood begin to dip? What you’re feeling isn’t weakness—it’s biology, and you can change it.

If you're like most people, you prefer the "longer days" and later sunsets of summer—yet there's good reason you feel a shift in your mental state, sleep needs, and even productivity during the late fall and winter.

For thousands of years, our ancestors lived in harmony with the sun's natural rhythms, which meant working and resting in sync with the changing seasons.

But today, most of us spend our days indoors under artificial lights, disconnected from the sunlight that does so much to sustain our health.

In this article, we’ll explore why sunlight and vitamin D are vital during all times of the year, including the darker months, how low levels can impact your energy and immunity, and the Biblical and scientific ways to stay strong, joyful, and full of life through winter.

Why Vitamin D Deficiency Is Common in Winter

Vitamin D deficiency affects over 1 billion people globally, and during winter months, low sun exposure makes it even more widespread. This deficiency contributes to fatigue, weakened immunity, and mood changes that mirror the seasonal cycle itself.

The Power of Sunlight and Vitamin D for Health

Sunlight is one of God’s and nature's simplest and most powerful medicines. When light from the sun hits your skin, your body produces vitamin D, a hormone-like nutrient that regulates over 1,000 genes related to immune health, metabolism, mood, and brain function.

From a Biblical perspective, light symbolizes vitality, hope, and divine order. In Genesis 1:3, God said, “Let there be light,” and from that moment, life was set in motion.

In fact, studies show that people with healthy vitamin D levels—who are very likely to spend enough time outdoors in sunlight—have a lower risk of fatigue, depression, respiratory infections, and chronic diseases like diabetes and heart disease.

For example, a meta-analysis found that people who were supplemented with vitamin D had a 20% lower risk of acute respiratory infections, especially during colder months when sunlight exposure was lowest.

Here’s what vitamin D does for your health:

Activates immune defenses: Helps produce antimicrobial peptides that fight off bacteria and viruses.
Regulates inflammation: Balances immune responses, reducing chronic inflammation that contributes to autoimmune and metabolic diseases.
Supports bone strength: Enables calcium absorption and works synergistically with vitamins A and K2 to prevent brittleness.
Boosts mood and brain health: Supports serotonin production and reduces the risk of depression, particularly in darker months.
Enhances cardiovascular and metabolic health: Low vitamin D levels are linked to higher inflammation and increased risk of insulin resistance, weight gain, and hypertension.

Unfortunately, many people fall into the deficiency category. One large review found that vitamin D deficiency is now a global epidemic affecting over 1 billion people worldwide, and an estimated 40% to 50% of the U.S population (including more than 60% of older people living in nursing homes).

Why Lack of Sunlight Leads to Fatigue and Low Mood

When we spend our days in darkness, we often lose our upbeat energy, mental clarity, and even drive and sense of purpose. In other words, even if you go to great lengths to eat well and exercise, simply missing out on daily sunlight can leave your body short on a critical nutrient.

Winter, much like rainy days, is notorious for making people feel sluggish and down, and lack of sunlight is one major reason why. This isn’t just psychological; reduced sunlight means your body produces less vitamin D and serotonin, both of which are essential for regulating mood and sleep.

According to research, low vitamin D levels are strongly linked to seasonal affective disorder (SAD), a form of "winter depression" marked by lethargy, brain fog, and cravings for sugar or carbs. Natural light, movement, and vitamin D are proven remedies for seasonal affective symptoms.

In ancient times, people adapted naturally to the seasons, including by eating what the earth provided, resting more, and spending time near fires that emitted full-spectrum light.

Today, artificial lighting and screens confuse our circadian rhythms, disrupting melatonin production and robbing us of restorative sleep.

5 Biblical and Scientific Ways to Stay Energized This Winter

1. Seek the Sun Whenever You Can

Even short bursts of midday sun exposure can have major benefits for your physical and mental health and help boost energy naturally.

Aim to spend 15–30 minutes outdoors daily with your face, arms, or legs exposed to the sun without sunscreen (unless you're in the sun for longer periods and are at risk of burning).

Remove sunglasses for part of that time to allow light to stimulate the retina in your eyes and reset your circadian rhythm.

If you live in northern regions, consider using full-spectrum or red light therapy lamps in the morning. Findings from certain studies show that red and near-infrared light can help improve mood, energy, alertness, and sleep quality by stimulating mitochondrial function, essentially mimicking the rejuvenating effects of natural sunlight.

2. Supplement with Vitamin D3 + K2

During the winter, sunlight—being weaker and less available—often isn’t enough to keep your vitamin D levels optimal (which is between 50–80 ng/m).

Studies show that supplementing with between 2,000–5,000 IU of vitamin D3 daily, especially during the winter months, can help maintain immune function, bone strength, and mood stability.

According to research, those who maintain healthy vitamin D levels through winter experience about 40% fewer respiratory infections and greater resilience to fatigue and low mood.

Pairing D3 with vitamin K2 is also a wise move since this combination helps to keep calcium directed into your bones, not your arteries, where it can contribute to heart-related issues.

3. Eat God-Created, Vitamin D–Rich Foods

Biblical foods like wild-caught fish, eggs, and organ meats are natural sources of vitamin D (although sunlight is still the best), along with nutrients like omega-3s and choline that nourish brain and nerve function.

These ancient staples supported people's mental health and vitality long before vitamin D supplements existed. For example, some research suggests that people who consume oily fish at least twice per week may have significantly fewer mood and neurological disturbances than those who don’t.

Focus on these natural vitamin D foods to help strengthen your immune and nervous system:

Wild-caught salmon and sardines: Rich in vitamin D and omega-3s for brain and heart health.
Egg yolks: A biblical staple loaded with choline for nervous system function.
Liver, organ meats, and grass-fed butter: High in vitamins A and D for energy and immunity.
Grass-fed beef: Offers some vitamin D, protein, and iron for strength.
Mushrooms (sun-dried or UV-exposed): A plant-based source of vitamin D2.

4. Honor the Rhythm of Rest

Winter is not a punishment—it’s an invitation to slow down. Scripture reminds us, “To everything there is a season” (Ecclesiastes 3:1).

Your metabolism naturally shifts during shorter days, favoring rest and recovery. Instead of fighting this, work with it:

Go to bed earlier and wake up naturally.
Turn off bright screens after sunset and spend time in quiet prayer or reading Scripture.
Rest as worship—it acknowledges that strength comes from the Creator who renews you daily.

When you embrace the darker days and allow yourself to move a bit slower, you’ll notice calmer evenings, deeper sleep, and a greater sense of well-being.

5. Move Daily—Even When You Don’t Feel Like It

Movement generates internal warmth and helps boost energy naturally. Exercise increases circulation, improves brain function, and lifts your mood.

Research shows that even a 20-minute walk outdoors can help reduce stress hormones and fatigue for the rest of the day. Studies also show that exercise is as effective as some medications for fighting depression.

If you can, combine movement with sunlight—walking, gardening, or breathing deeply outdoors.

If the weather is cold, use indoor alternatives: rebounding, stretching, or bodyweight workouts to keep your lymphatic system active and your mood elevated.

Combine movement with worship: walk and pray, stretch and give thanks, or take “praise breaks” throughout your day. Aim for consistency, not necessarily intensity.

Consistency is key — small daily rhythms restore energy and joy even when sunlight is scarce.

Putting it All Together: A Daily Winter Routine for Energy & Mood Support

Morning:

Step outside within 10–30 minutes of waking.
Move gently: walk, stretch, or do light exercise.
Eat a protein-rich breakfast with eggs or fish.
Begin your day with gratitude and prayer.

Midday:

Take a short outdoor break.
Drink filtered water with sea salt or trace minerals.
Take vitamin D3 + K2 with your largest meal.

Evening:

Dim the lights to mimic nature’s rhythm.
Disconnect from screens one to two hours before bed.
Aim for 7–9 hours of sleep in a cool, dark room.

Weekly Rhythm Tip:
Spend time outdoors on the Sabbath, even in cold weather. Rest, gratitude, movement, and natural light recharge both body and spirit.

Final Thoughts: Choosing Light in the Darkness

Just as the earth rests and renews itself in winter, our bodies and souls can use this time for restoration. Yet, to thrive (not just survive), we must stay connected to the light that nature provides.

By aligning your habits with creation’s design—seeking sunlight, nourishing your body, honoring rest, and feeding your spirit—you can remain energized, joyful, and healthy even in the darkest and coldest months.

Stay connected to the Creator’s light by caring for your body and rhythm the way He designed.

References:

https://pubmed.ncbi.nlm.nih.gov/28202713/

https://pubmed.ncbi.nlm.nih.gov/28678771/

https://pmc.ncbi.nlm.nih.gov/articles/PMC10607188/

https://www.nccih.nih.gov/health/providers/digest/seasonal-affective-disorder-and-complementary-health-approaches-science

https://www.ncbi.nlm.nih.gov/books/NBK532266/

https://health.ucdavis.edu/blog/cultivating-health/3-ways-getting-outside-into-nature-helps-improve-your-health/2023/05

https://pmc.ncbi.nlm.nih.gov/articles/PMC6042449/

https://pmc.ncbi.nlm.nih.gov/articles/PMC8208091/

https://pmc.ncbi.nlm.nih.gov/articles/PMC10484593/

https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/