Introduction
In "Chasing the Sun," author Linda Geddes explores the profound impact that sunlight has on our health, well-being, and daily lives. This eye-opening book delves into the intricate relationship between humans and the sun, drawing on scientific research and historical evidence to illustrate just how crucial sunlight is for our physical and mental health.
From ancient civilizations that worshipped the sun to modern scientific studies, Geddes presents a compelling case for why we should pay more attention to our exposure to natural light. The book covers a wide range of topics, including the body's internal clock, the healing power of sunlight, the dangers of artificial light, and innovative approaches to managing our relationship with the sun in today's world.
The Body's Internal Clock
One of the central themes in "Chasing the Sun" is the concept of our internal clock, also known as the circadian rhythm. Geddes explains that each of us has a master clock called the suprachiasmatic nucleus (SCN), located in the hypothalamus of our brain. This tiny group of cells coordinates our body's daily functions, ensuring that various processes occur at the right time.
The SCN is responsible for regulating:
- Hormone production
- Blood pressure
- Body temperature
- Energy levels
- Sleep-wake cycles
What's fascinating is that this internal clock is primarily influenced by the sun. When we're exposed to sunlight in the morning, it signals our body to wake up, increase alertness, and prepare for the day ahead. Conversely, as the sun sets and light fades, our body begins to wind down and prepare for sleep.
Geddes highlights how deeply ingrained these rhythms are in our DNA, tracing them back to primitive cyanobacteria from which human life evolved. She draws parallels between humans and plants, noting that flowers like morning glories and petunias have their own circadian rhythms tied to sunlight.
Understanding the importance of these internal clocks helps explain why disruptions to our natural light exposure can have such significant impacts on our health and well-being.
The Healing Power of Sunlight
The book takes us on a journey through history, exploring how various cultures have recognized and harnessed the healing power of sunlight. Geddes discusses the ancient practice of heliotherapy, or sun therapy, which was used by the Romans and Greeks to treat a variety of ailments.
Some historical uses of heliotherapy included treating:
- Epilepsy
- Anemia
- Asthma
- Jaundice
- Obesity
While these ancient practices may seem primitive, Geddes points out that modern science has validated many of the benefits of sun exposure. For example, researchers in the early 20th century discovered that sunlight and ultraviolet light could effectively treat tuberculosis of the skin.
One of the most significant discoveries related to sunlight's healing properties is its role in vitamin D production. Geddes explains how human skin produces vitamin D in response to sunlight exposure, which is crucial for maintaining healthy bones and preventing skeletal disorders like rickets.
The author shares a fascinating historical anecdote about the rise of rickets in England during the Industrial Revolution. As more people moved to work in factories, spending long hours indoors, rickets became a widespread problem. The discovery of vitamin D and the promotion of heliotherapy helped cure many people of this condition.
Geddes also discusses more recent research suggesting that vitamin D is particularly important for pregnant women, especially in the second half of pregnancy, as it may help prevent newborns from developing multiple sclerosis later in life.
The Dangers of Artificial Light
While "Chasing the Sun" emphasizes the benefits of sunlight, it also warns about the potential dangers of too much artificial light exposure. Geddes points out that many people today spend most of their time indoors under artificial lighting, which can disrupt our circadian rhythms and lead to various health problems.
The author provides some eye-opening statistics:
- The average British office worker gets only 587 lux of daily sun in summer and 210 lux in winter.
- Most workplaces are at least ten times dimmer than outdoors on the cloudiest winter day.
- In contrast, the average Amish person in Pennsylvania, who works outdoors, gets 4,000 lux of daytime light in summer and 1,500 lux in winter.
These figures highlight the dramatic difference in light exposure between our modern, indoor-centric lifestyles and more traditional, outdoor-focused ways of living.
Geddes explains that spending too much time under artificial light can have serious consequences for our health. It can interfere with our body's natural signals for day and night, making it difficult to maintain a healthy sleep-wake cycle. This is particularly problematic when it comes to blue-white light emitted by computer and smartphone screens, which can delay the release of melatonin, the hormone that prepares our body for sleep.
To illustrate the impact of artificial light, Geddes shares her personal experiment of switching to candlelight in her home for a month. While the amount of sleep she got didn't change, she found that her sleep felt deeper and more restful, and she woke up feeling more energized – all signs of improved circadian rhythm function.
The Link Between Light and Cancer
One of the more alarming revelations in "Chasing the Sun" is the potential link between circadian disruption and cancer. Geddes cites the International Agency for Research in Cancer, which has classified circadian disruption as "probably carcinogenic to humans."
To illustrate this point, she shares the story of Seth Burton, a former US Navy submarine captain who believes that the constant circadian disruption he experienced during his career contributed to his later cancer diagnosis. Burton's crew lived in an environment with no access to sunlight and operated on an 18-hour day, causing severe disruption to their natural rhythms.
While the exact mechanisms are still being studied, research on mice suggests that such disruptions to circadian rhythms can indeed be carcinogenic. This underscores the importance of maintaining regular exposure to natural light cycles for our overall health and well-being.
Seasonal Affective Disorder and Light Therapy
Geddes devotes significant attention to the impact of light on our mental health, particularly focusing on Seasonal Affective Disorder (SAD), also known as the "winter blues." This mood disorder is common in areas with little winter sunlight and can have a significant impact on people's quality of life.
The book explores various approaches to combating SAD, including:
Light boxes: These devices simulate sunlight and have been shown to alleviate SAD symptoms after a few days of use.
Sun mirrors: Geddes describes the innovative solution implemented in Rjukan, Norway, where sun mirrors installed in the mountains reflect sunlight into the town, providing two extra hours of direct sunlight on clear days.
Sauna and cold water immersion: In Sweden, a popular cure for SAD involves time in a sauna followed by a dip in frigid waters. Geddes explains the science behind this ritual, noting that both the heat and cold trigger beneficial physiological responses in the body.
These examples highlight the creative ways in which people have adapted to cope with limited sunlight exposure, emphasizing the importance of light in maintaining our mental health.
Chronotherapy for Depression and Bipolar Disorder
One of the most intriguing sections of "Chasing the Sun" focuses on the emerging field of chronotherapy as a treatment for severe mental health conditions like chronic depression and bipolar disorder. Geddes introduces us to Dr. Francesco Benedetti, a psychiatrist at the San Raffaele Hospital in Milan, who has been using chronotherapy to treat patients for over two decades.
The book shares the story of Maria, one of Dr. Benedetti's patients who has experienced remarkable improvements in her severe depression through a treatment called triple chronotherapy. This approach combines:
- Light therapy
- Mood-stabilizing medication (lithium)
- Occasional nights of sleep deprivation
Geddes explains that this treatment works by resetting the patient's circadian rhythms, which are closely tied to the release of neurochemicals like serotonin. The results have been impressive, with about 70% of patients experiencing positive outcomes, even when they didn't respond well to traditional antidepressant medications.
This section of the book highlights the potential for innovative, light-based treatments to revolutionize mental health care, offering hope for those who struggle with severe mood disorders.
Rethinking Our Relationship with Time
In the latter part of "Chasing the Sun," Geddes explores how our modern society's rigid adherence to clock time often conflicts with our natural circadian rhythms. She introduces us to Michael Wieden, a business manager in the German town of Bad Kissingen, who has been campaigning for a more flexible approach to time that better aligns with people's internal clocks.
Wieden's efforts include:
- Pushing for a looser schedule that accommodates different chronotypes (e.g., "night owls" and "larks")
- Advocating for the town to opt out of Daylight Saving Time (DST)
While Wieden's most controversial proposal was ultimately rejected by the town council, his campaign highlights the growing awareness of the importance of aligning our schedules with our natural rhythms.
Geddes also discusses the impact of early school start times on teenagers, whose natural sleep patterns often conflict with traditional school schedules. She cites examples of schools in Edina, Minnesota, and England that have shifted to later start times and seen significant improvements in student attendance, performance, and overall well-being.
These case studies demonstrate that small changes in how we structure our days can have profound effects on our health and productivity.
Practical Applications and Future Directions
Throughout "Chasing the Sun," Geddes provides numerous examples of how individuals, schools, and businesses are beginning to take circadian rhythms seriously. Some of the practical applications and trends she discusses include:
- Installing indoor lighting that better mimics natural sunlight patterns
- Allowing more flexible work schedules and remote work options
- Designing buildings with more natural light exposure
- Encouraging outdoor time during the workday or school day
The author suggests that as our understanding of circadian rhythms and the importance of natural light exposure grows, we may see more widespread changes in how we structure our lives and built environments.
Conclusion
"Chasing the Sun" presents a compelling case for the vital importance of sunlight in our lives. Linda Geddes weaves together historical evidence, cutting-edge scientific research, and personal anecdotes to create a comprehensive picture of how profoundly the sun affects our physical and mental well-being.
Key takeaways from the book include:
- Our internal clocks are deeply influenced by the sun and play a crucial role in regulating bodily functions.
- Exposure to natural light is essential for maintaining good health, including proper vitamin D production and mental well-being.
- Artificial light, especially at night, can disrupt our circadian rhythms and potentially lead to serious health issues.
- Innovative light-based therapies show promise in treating mental health conditions like depression and bipolar disorder.
- Rethinking our societal relationship with time and light exposure could lead to significant improvements in public health and productivity.
Geddes' work serves as a wake-up call, urging readers to pay more attention to their relationship with the sun and natural light cycles. By understanding and respecting our body's innate rhythms, we can take steps to improve our health, mood, and overall quality of life.
As we move forward in an increasingly indoor, screen-dominated world, the lessons from "Chasing the Sun" become ever more relevant. The book encourages us to find ways to incorporate more natural light into our daily lives and to be mindful of how our modern lifestyles may be affecting our internal clocks.
Ultimately, "Chasing the Sun" reminds us of our deep, evolutionary connection to the sun and the profound impact it has on every aspect of our being. By reconnecting with this fundamental force of nature, we may find the key to better health, happiness, and harmony in our lives.