Written By: GreenMedInfo Research Group

For thousands of years, the rising and setting sun governed human biology. Now, researchers are uncovering how recreating these natural light cycles can dramatically improve our health in the modern world.

The Evolutionary Basis of Light's Impact on Health

Long before the invention of artificial lighting, humans evolved intricate biological rhythms tied to the daily cycles of sunlight. The warm red and orange hues of dawn and dusk acted as powerful cues to regulate our circadian rhythms, hormones, and countless other physiological processes.

Dr. Richard Stevens, cancer epidemiologist at the University of Connecticut, explains: "Electric lights, especially at night, disrupt circadian rhythms through melatonin suppression and phase shifting. The health consequences are broad, including sleep disruption, depression, cardiovascular disease, and cancer."1

By understanding and recreating the essential wavelengths of natural light cycles, we may be able to mitigate many of the health issues caused by modern lighting and screen use.

The Science Behind Dawn and Dusk Light

Recent research has identified the specific light wavelengths that most powerfully influence our circadian biology:

• Blue light (450-495 nm): Suppresses melatonin production, increases alertness
• Green light (495-570 nm): Improves alertness and cognitive performance  
• Red/near-infrared light (600-1000 nm): Stimulates mitochondrial function, promotes healing

A groundbreaking 2019 study by Bromundt et al. found that simulating natural dawn-dusk cycles using these wavelengths produced significant benefits in dementia patients:

"Dawn-dusk simulation led to significantly better mood in the morning hours after waking. The effects were most pronounced in the second 4 weeks with DDS, indicating that positive effects emerged gradually."2

The researchers concluded that "continuous, long-term application of dawn-dusk simulation at the sleep-wake transitions appears to increase external zeitgeber strength" - essentially reinforcing the body's natural circadian rhythms.

Incorporating Natural Light Cycles in Modern Life

While getting outside for actual sunrise and sunset is ideal, there are several ways to mimic these beneficial light wavelengths in our indoor environments:

• Use red/amber lighting in the evening hours
• Install dawn simulator alarm clocks  
• Wear blue-blocking glasses after sundown
• Enable Night Shift/f.lux on devices to filter blue light
• Use red night lights instead of white/blue
• Consider light therapy boxes for morning light exposure

Dr. George Brainard, Director of the Light Research Program at Thomas Jefferson University, advises: "The key is to get bright light, preferably sunlight, during the day and then dim, longer wavelength light in the evening. This will help keep your circadian rhythms appropriately synchronized."3

Therapeutic Applications of Light

Beyond general wellness, targeted light therapy shows promise for treating various health conditions:

• Seasonal affective disorder
• Non-seasonal depression
• Sleep disorders
• Dementia and cognitive decline
• Chronic pain

A 2003 study by Fontana Gasio et al. found that even low-intensity dawn-dusk simulation improved sleep timing and quality in elderly dementia patients:

"The main sleep episode was 1:14h earlier during treatment (p=0.03) compared with before and after DDS. With respect to actimetry-determined sleep variables, the DDS group tended to have shortened 'sleep latency', longer 'sleep duration', more nocturnal immobility and less nocturnal activity than the dim red group (p<0.1)."4

Conclusion

By understanding and harnessing the power of natural light cycles, we can dramatically improve our health and wellbeing in the modern world. Simple changes to our light environment - both during the day and at night - can help realign our bodies with the rhythms we evolved with for millennia. As research in this field progresses, light-based therapies are likely to play an increasingly important role in both preventative health and medical treatments.

© September 2nd 2024 GreenMedInfo LLC. This work is reproduced and distributed with the permission of GreenMedInfo LLC. Want to learn more from GreenMedInfo? Sign up for the newsletter here www.greenmedinfo.com/greenmed/newsletter.