Light, Circadian Rhythm, and Hormones
The Influence of Light on Our Physiology
Our light environment affects everything from hormone regulation, fertility, digestion, sleep cycles, thyroid health, to detoxification and healing processes. Artificial light exposure disrupts our circadian rhythm, impacting our hormonal balance and overall health.
Understanding Circadian Rhythm and Hormones
Our circadian rhythm, a 24-hour internal clock, regulates how our cells function. Light cycles, interpreted by receptors in our eyes, signal to our brain and cells, orchestrating hormone a specific cascade of hormone production. Blue light from the morning sun activates these receptors, sending signals to the brain’s hypothalamus, which then directs metabolic activity, including hormone regulation.
Hormone Signaling and Light
Mitochondria Activation: Blue light stimulates the mitochondria in endocrine glands (thyroid, ovaries, adrenals) to produce pregnenolone, the master hormone. Pregnenolone is converted into stress (adrenaline, cortisol) and sex hormones (DHEA, testosterone, estrogen, progesterone).
HPA Axis Activation: The hypothalamus-pituitary-adrenal axis releases cortisol, creating a wake-up response. Cortisol peaks in the morning and tapers off as the day progresses or at least its supposed to.
HPT Axis Activation: The hypothalamus-pituitary-thyroid axis, activated by UVA light, helps convert tyrosine into thyroid hormone, crucial for metabolism.
Light, Sleep, and Melatonin
Morning light exposure breaks down melatonin from sleep into tryptophan, which uses UVA light to make serotonin. This serotonin converts back to melatonin at night, but only if blue light exposure is minimized in the evening. Artificial light and screens can suppress melatonin production by over 80%, disrupting sleep and healing processes plus it will create a surge of cortisol that impacts our sleep further.
Impact of Artificial Light
Natural blue light from sunlight keeps our biological clock running smoothly. However, artificial light, with its constant high-intensity blue light, tricks our body into thinking it's always midday. This disrupts our biological clock, affecting digestion, sleep, fertility, hormones, and detoxification.
If you struggle to start your day, it might be due to insufficient tryptophan-to-serotonin conversion, affecting dopamine and cortisol balance. Serotonin also aids gut motility, enzyme activation, and good gut bacteria. Without proper conversion to melatonin at night, we end up feeling wired but tired, impacting sleep and repair mechanisms.
Reflective Questions
What is your relationship with natural light?
Do you work under fluorescent lighting all day?
Do you watch TV at night or check your phone first thing in the morning?
How can you incorporate more natural light into your daily routine?
How can you set a positive example for your family?
Tips to Repair Your Circadian Rhythm
Morning Exposure: Get outside as close to sunrise as possible for 3-5 minutes without windows or sunglasses.
Mid-Morning Walk: Schedule a 20-minute walk during the UVA window (generally mid-morning).
Frequent Outdoor Breaks: Take at least 5 minutes outside throughout the day. Rain or Shine to get in more natural light through the eyes.
Evening Adjustments: Dim lights, wear blue-blocking glasses, or use different light bulbs in the evening.
Remove Technology from the bedroom and don’t watch screens at least a few hours before bed.
Start with just 30 seconds and gradually increase to 3-5 minutes as the seasons change. Make it manageable for your lifestyle.
Additional Resources
Circadian App: Track peak light exposure windows based on your location.
Carrie B Wellness: For more education and blue-blocking glasses recommendations.
Iris: A screen protector app for different times of the day for your computer.
Dimmer Systems: Install in your home.
Red Light Bulbs: Use for evening lighting.
By making these small changes, you can better support your circadian rhythm and overall hormonal health.