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Light exposure, particularly morning and evening sunlight exposure, has a profound impact on setting and resetting our circadian rhythm, our mood, cognitive function and overall health.

Thankfully, our awareness of mental health and wellness, understanding how natural light influences our daily lives has become a topic of great interest. Today we explore some of the benefits sunlight exposure can play in maintaining our well-being.

Understanding Circadian Rhythm

The circadian rhythm is an internal body clock that regulates the sleep-wake cycle and repeats roughly every 24 hours. This timing is different for every person, which, from an evolutionary perspective, is a good thing. This ensured there was always someone in the tribe who was awake for our safety. (Finding one’s chronotype is a topic we’ll discuss next time). Today this is not so important, but for shift-workers, this is just one way to alleviate the negative effect of changing sleep patterns. Natural light is one of the most significant factors affecting the regulation of our circadian rhythm. Exposure to light, helps set this internal clock, promoting better sleep patterns and overall health.

Benefits of Morning Sunlight Exposure

Morning sunlight exposure is essential for regulating sleep patterns. Even moderate amounts of sleep deprivation has been linked to mental health issues. When the eyes detect natural light, they send signals to the brain’s suprachiasmatic nucleus (SCN), which in turn signals the production of melatonin, a hormone that regulates sleep. Morning light exposure helps suppress melatonin production, making us feel more awake and alert during the day. Consistent morning sunlight exposure helps maintain a regular sleep schedule, reducing the likelihood of insomnia and other sleep disorders. A “Phase Advance” occurs with the slight shift, moving your circadian rhythm earlier with morning sunlight exposure.

Boosts Mood and Reduces Depression

Natural light exposure, particularly in the morning, has been shown to boost mood and reduce symptoms of depression. Sunlight increases the release of serotonin, a hormone associated with mood elevation and feelings of well-being. This is particularly beneficial for individuals suffering from Seasonal Affective Disorder (SAD), a type of depression that occurs at certain times of the year, typically in the winter months in countries away from the equator, when sunlight exposure is limited.

Enhances Cognitive Function

Exposure to natural light in the morning can enhance cognitive function and improve concentration. Studies have shown that individuals who receive adequate morning light perform better on cognitive tasks and have improved memory and attention span. This can be particularly beneficial for students and professionals who need to maintain high levels of productivity throughout the day.

Supports Eye Health

Morning sunlight exposure can also benefit eye health. It helps regulate the production of dopamine in the retina, which is crucial for maintaining good vision. Additionally, spending time outdoors in natural light reduces the risk of developing near-sightedness, especially in children and adolescents.

Evening Light Exposure: Benefits and Considerations

While morning sunlight exposure is critical, evening light exposure also has its benefits when managed correctly. Conversely to morning sunlight exposure, evening light exposure causes a “Phase Delay” which delays your circadian rhythm. This constant balance helps establish “when” your body is in relation to natural light cycles and continually calibrates us.*

Vitamin D Synthesis

Although less intense than morning or midday sunlight, evening sunlight still contributes to the body’s synthesis of vitamin D, which is vital for bone health, immune function, and overall well-being.

Optimizing Light Exposure for Health

To optimize the benefits of light exposure, it’s essential to balance morning and evening light correctly. Here are some practical tips:

Morning Routine: Within the first hour of waking, aim to spend around ten minutes outside in the morning sunlight. If the weather is cloudy, try doubling that time. The same benefits can be achieved in cloudy conditions. Whether it’s a walk, run, or simply enjoying a cup of coffee on the balcony, morning light exposure sets you up each day for the range of health benefits mentioned.

Daytime Breaks: If possible, take breaks during the day to step outside and get some sunlight. This can help maintain alertness and productivity.

Evening Activities: Try the same timing as the morning sunlight exposure protocols suggest. Engage in relaxing activities during the evening that expose you to natural light but avoid bright artificial lights before bedtime, as they can interfere with melatonin production. Avoid the exposure to Blue light (light emitted from screens and UV lights) between the hours of 10pm and 4am.

Smart Lighting: Use dim, warm lighting in the evening to mimic natural light patterns and avoid screens at least an hour before bed to promote better sleep. If possible, reduce the amount of lighting in your environment by at least 50% (if safe to do so) around the time the sun goes down. Red light bulbs can be used around your home (any type – including ‘party’ lights) to signal the brain that the timing for sleep is soon.

The wrap-up

Incorporating morning and evening sunlight exposure into your daily routine can help to regulate your circadian rhythm, boost mood, enhance cognitive function, and support overall health. Evening light exposure, when balanced correctly, also offers relaxation and social benefits. By understanding and harnessing the power of natural light, you can enhance your well-being and lead a healthier, more balanced life.

*As a side note, during the many lockdowns around the world during the recent pandemic, it was reported that the isolation causing people to spend more time on their devices had a massive effect on shifting the circadian rhythm of people to much later, causing what has been termed as “Social Jetlag”.

Here is a link to an interesting study done by The University of Colorado Bolder, showing the effect of natural light exposure and how the body’s natural rhythms are affected.

https://www.cell.com/current-biology/fulltext/S0960-9822(16)31522-6

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