Why Light is So Crucial to Your Health

How does light shape your day and night?

Sunlight, a seemingly simple element of our daily lives, holds an extraordinary power that significantly impacts our health and well-being. Associate Professor of Clinical Neuroscience at the University of Oxford, Aarti Jagannath, asserts, “Every aspect of how we function is controlled by light.” This statement underscores the profound influence light, especially sunlight, has on our physical and mental health.

In modern life, particularly during winters in places like Canada, our exposure to natural sunlight diminishes drastically. A renowned geneticist, Steve Jones, warns about the “perils of living without sunlight,” highlighting the severe consequences of inadequate or poorly timed light exposure.

Historical experiments, such as those conducted by French researchers in the 1960s involving prolonged stays in caves, revealed drastic disruptions in sleep patterns and severe mood disturbances, including depression. These findings underscore the importance of light in regulating our natural rhythms and maintaining mental health.

Short on time to read? Here are my top tips for managing light exposure for better sleep and wellbeing:

1. Seek Morning Sunlight: Spend time outside in natural light, especially in the morning, to help set your circadian rhythm.
2. Limit Evening Blue Light: Reduce exposure to blue light from screens in the evening to avoid disrupting sleep hormones.
3. Use Light Therapy: If natural light is scarce, especially in winter, consider using a light therapy box to mimic sunlight.
4. Maintain Regular Sleep Patterns: Head to bed around the same time, ideally when you’re feeling sleepy, and wake up at the same time every day, even on weekends, to reinforce your natural sleep-wake cycle.
5. Create a Dark Sleep Environment: Ensure your bedroom is dark at night; use blackout curtains or an eye mask if necessary.
6. Limit Caffeine and Alcohol: Avoid these stimulants in the evening as they can disrupt sleep patterns.
7. Outdoor Exercise: Engage in physical activity outdoors to benefit from both exercise and natural light exposure.
8. Healthy Diet: Consume a balanced diet rich in nutrients to support overall health and sleep quality.
9. Consult Health Professionals: If sleep problems persist, seek advice from healthcare providers to assess and treat any sleep disorders and develop personalized strategies.

The Circadian Rhythm: Our Internal Clock

At the heart of our body’s response to light is the circadian rhythm, an internal timer set to a 24-hour cycle in all life forms. This rhythm is crucial in timing all our physiological processes and behaviours. Jagannath explains, “The circadian rhythm is set every day by the rising of the sun,” orchestrating the active processes during the day and restorative processes at night. Dawn light, particularly, is essential for timing our circadian rhythm.

The wavelengths of light that most powerfully impact our circadian rhythm are in the bluish spectrum. Within our eyes, specific cells contain a pigment sensitive to this blue light, which signals to the body clock, helping it discern the time of day. These ganglion cells, which detect light levels but are unrelated to vision, are crucial for setting circadian rhythms, even in many individuals who are blind.

People with complete blindness commonly experience Non-24-Hour Sleep-Wake Disorder. This can cause problems because their bodies are not synched with the 24-hour cycle between day and night.

The Consequences of Disrupted Light Exposure

Many people feel somewhat out of sorts in the darker fall and winter months, a condition often exacerbated by reduced sunlight exposure. This lack of natural light negatively affects the immune system and defence mechanisms. A disrupted circadian clock can lead to mood fluctuations, increased depression, metabolic disorders, and other health issues.

Modern lifestyles, often characterized by prolonged indoor activities and exposure to artificial light, exacerbate these problems. For those working night shifts, the situation is even more pronounced. In Canada, it’s estimated that over 1.8 million people work night shifts; in the UK, over 3 million people work night shifts, often leading to the desynchronization of bodily systems.

This misalignment can increase the risk of diabetes, obesity, cardiovascular diseases, and other health issues. According to Jagannath, “97% of shift workers never adjust their sleep cycles,” highlighting the widespread impact of irregular light exposure on our health.

People who work the night shift are at greater risk for health problems. In a recent study of over 85,000 subjects in the UK, low daylight and high exposure to artificial light at night were correlated with a greater risk of developing depression, anxiety, and other mental health issues.

While studies like this don’t prove that poorly timed light exposure causes these issues, it does add to the growing body of research that shows again and again that getting outside and avoiding light at night is a simple and potentially very effective non-drug means to improve overall physical and mental health.

The Role of Vitamin D and Outdoor Exposure

One of the most critical roles of sunlight is in synthesizing Vitamin D, an essential component for various signalling pathways in our body. Steve Jones points out that while Vitamin D can be supplemented through diet or pills, the most effective source is sunlight. Vitamin D deficiency, linked to diseases such as rickets and tuberculosis, is seeing a resurgence due to decreased sunlight exposure.

Embracing Natural Light for Health and Well-being

Decreased outdoor activities and reliance on artificial light push us towards a lifestyle reminiscent of “hermits in a cave.” To counteract this, experts recommend simple yet effective strategies: maintaining regular meal and sleep times and ensuring daily exposure to natural light, even for short periods.

A study at the Broadmoor Institute found that the equivalent of 20 minutes of bright morning sunshine significantly elevates mood more effectively than some anti-depressants. Other studies have shown that 20 minutes outside improves mood, even on a cloudy day. These findings illustrate the profound impact that even brief exposure to natural light can have on our mental health.

Conclusion: Heed Nature’s Call

As we navigate the complexities of modern life, it’s crucial to remember the fundamental role that natural light plays in our health. “Don’t retreat into your cave,” advises Jones. Instead, we should embrace the sun and outdoor activities for physical and mental well-being.

In the words of Robert Louis Stevenson, who succumbed to tuberculosis in 1894, the winter landscape, “frosted like a wedding-cake,” is a reminder of the beauty and importance of the natural world.

Let us heed nature’s call, stepping out into the light to help keep our internal clocks in sync and nurture our health and vitality.

Trouble sleeping? Contact me today to schedule your free virtual consultation and begin your journey to good nights and better days.

To learn more about sleep health and science-backed tips to improve your mental health, visit our Blog.