April/May Seasonal Update: The Rapid Increase in Sunlight

In a Nutshell

Sunlight is a key driver of life’s rhythms, including our own health and vitality
A healthy circadian rhythm is essential for physical and mental well-being
Late spring allows me to eat more locally, move more, and generally engage comfortably with the natural world

This Month’s Update: Why Sunlight Matters So Much

This month, I’m taking a slightly different approach. Rather than diving straight into what’s happening in my garden, on the land, or along the shoreline, I want to explore why one of the season’s biggest changes - sunlight - is so important for human health.

I’ve touched on sunlight before, but this time I’m focusing on its deep connection to our biology: how sunlight sets our natural rhythms, and why aligning with this rhythm is essential for long-term health.

Sunlight: The Foundation of Life

For more than three billion years, life on Earth has adapted to and depended on sunlight. Early single-celled plankton not only captured sunlight for energy but also developed natural defenses against its potential harm [1]. These foundational systems - light capture and biological safeguards - are still embedded in the biology of plants and animals (including humans) today.

This means something profound: Sunlight isn’t just a nice-to-have, it’s a requirement for life. Without it, human biology doesn’t function properly. If I’m serious about living my best life, with real food and vibrant health, I must also embrace sunlight.

Circadian Rhythms: Why Timing Matters

All plants and animals - including us - live by an internal 24-hour clock known as the circadian rhythm. This rhythm allows our bodies to:

“Prepare for and adapt to environmental changes on a regular basis - like winter’s arrival, seasonal foods, animal migrations, and climate shifts”

— Reference 3

A healthy circadian rhythm helps our body (and our microbiome) stay in sync with the world around us, finely tuning processes like metabolism, immune function, and repair cycles.

Where I live in the far north, the seasons are very noticeable:

In winter, I get only ~8 hours of daylight
In summer, it stretches to ~19 hours

These shifts tell my body when to conserve energy and repair (winter) and when to ramp up activity, build strength, and grow (summer). If my body couldn’t sense these changes—if my circadian rhythm was disrupted - I’d lose this critical ability to adapt.

How We Stay Aligned

Our circadian rhythm is tuned by the environment:

Sunlight: Through our skin, eyes, and deeper tissues
The Earth’s electrical charge: The ground beneath us supplies a steady negative charge
The Earth’s magnetic field: Fluctuates in a predictable rhythm, influencing many biological processes

Sunlight’s Deep Effects

Sunlight doesn’t just touch the skin. Red and infrared light penetrate deeper - reaching muscles, organs, and even bones (see Figure 1).

It also influences our gut microbiota.

The Cost of Circadian Disruption

When our circadian rhythm is out of sync, it’s linked to serious conditions [1,6] like:

Insulin resistance and metabolic disorders
Obesity and heart disease
High blood pressure, type 1 diabetes, multiple sclerosis, and even cancer

These connections are still being explored, but the risks are real

Why I’m Not Afraid of Sunlight

The benefits of natural sunlight have been understood for a long time. Consider rickets, a condition caused by too little vitamin D [1]:

“In the early 1930s the United States Government sent out a brochure to parents encouraging sunbathing for their infants “to help him grow naturally””

The relationship between sunlight and cancer is perhaps the least well understood today [1]:

“In 1915 it was reported that indoor workers had an 8-times times higher risk of dying of cancer compared to outdoor workers”

I’ve noticed that after removing industrial seed oils from my diet, I tolerate sunlight much better. I suspect those unstable fats were making my skin more prone to damage. Now, while I’m more comfortable in strong sun, I still protect myself with shade or UV-blocking clothing when needed.

One cautionary note: If your diet is full of processed foods (seed oils, refined carbs, sugary snacks), your metabolism is likely compromised - and you won’t fully benefit from sunlight or other natural rhythms.

What’s Happening Where I Live?

Sunlight

Daytime temperatures are rising, making it much easier to get safe, regular sun exposure. See Table 1 for the key habits I follow daily to maintain a healthy rhythm.

Table 1: Safe sun exposure in the Scottish spring time

Food

Local veggies are back in the shops and garden. Foraged foods are also available - ask local experts or try a couple of sources that might be useful

Herbalists without borders – monthly seasonal foraging guide poster
Online foraging app recommendations

North Sea seafood is excellent this time of year:

Bivalves (mussels, clams, oysters) thrive with the sunlight-driven nutrient surge
Mackerel and herring follow the spring plankton bloom inshore—delicious and nutrient-dense

See Table 2 for a summary of seasonal foods.

Table 2: Spring brings the start in growth of this year’s local food

Microbiome

Staying connected to the natural world helps maintain a healthy microbiome - especially through gardening and outdoor activities like mountain biking (see Table 3).

Earth’s Natural Charge

This is simple: expose your skin to the ground. Go barefoot, lie on the grass, or work with your hands in the soil. See Table 4 for ideas.

Table 4: Warmer temperatures make it easy to connect with the earth

Summary

As spring transitions into summer, the surge in sunlight is one of the most significant changes in the natural world - and it’s essential for our health.

Sunlight drives life’s rhythms. It’s not just about vitamin D; sunlight influences our circadian rhythm - the 24-hour internal clock that controls our metabolism, immune system, and repair cycles. Without sunlight, our body’s systems fall out of sync, increasing the risk of ill health.

Our bodies evolved to sense nature’s signals like sunlight, the Earth’s negative charge, and its magnetic field. These cues help us stay aligned with the seasons. For example:

In winter, our metabolism slows for rest and repair.
In summer, we’re primed for growth and activity.

Practical ways to align with the season:

Get safe, regular sunlight exposure
Eat seasonal, local foods—like spring greens, foraged plants, and nutrient-rich seafood (mussels, clams, mackerel)
Reconnect with the natural world: garden, bike, or simply get your hands in the dirt to support a healthy microbiome
Go barefoot or sit on the ground to absorb the Earth’s electrical charge

Final thought: Sunlight is life-giving—but its full benefits are unlocked when our diet and lifestyle support a healthy metabolism. Avoid industrially processed foods (especially seed oils) and embrace whole, seasonal foods to thrive in sync with nature.

References

Holick MF. Biological Effects of Sunlight, Ultraviolet Radiation, Visible Light, Infrared Radiation and Vitamin D for Health. Anticancer Res. 2016 Mar;36(3):1345-56. PMID: 26977036.
Mead MN. Benefits of sunlight: a bright spot for human health. Environ Health Perspect. 2008 Apr;116(4):A160-7. doi: 10.1289/ehp.116-a160. Erratum in: Environ Health Perspect. 2008 May;116(5):A197. PMID: 18414615; PMCID: PMC2290997.
Land, S. (2018) Metabolic Autophagy.
Ober, C. et al (2014) Earthing: The most important health discovery ever! Basic Health Publications, Inc.
Becker, R.O., Selden, G. (1985) Body Electric: Electromagnetism and the Foundation of Life. New York: William Morrow
Shi SQ, Ansari TS, McGuinness OP, Wasserman DH, Johnson CH. Circadian disruption leads to insulin resistance and obesity. Curr Biol. 2013 Mar 4;23(5):372-81. doi: 10.1016/j.cub.2013.01.048. Epub 2013 Feb 21. PMID: 23434278; PMCID: PMC3595381