By Dr. Tamara Kung, ND
The amount of time we are exposed to light has a profound influence over our physical and mental health. Light is a fundamental external cue and all living organisms have been exposed to it for eternity. It’s no wonder that every part of our biology is linked directly or indirectly with the light of the day and night.
In flowers for example, light signals them to open their petals to soak up sun for photosynthesis and the occasional pollination from a bee. At night, they protectively close their petals. In experiments when they are put in a greenhouse and are exposed to erratic light schedules (while still receiving the same amount of total light exposure as with natural light exposure), they wither away and die. In humans, phototherapy, or light as medicine, is being used to enhance health and well-being.
Why is that? What is light exactly, and how does it impact our health? And what do I do when the sun is behind the clouds for so many days?
In the most basic sense, light is a wave. We all know light is a spectrum (think Pink Floyd’s Dark Side of the Moon album) made up of various colours. Each colour, and those we cannot see like infrared and UV, have various lengths of waves. Infrared and red lights are long and drawn out. They can pass through our skin, penetrate into our organs, and even enter on a cellular level impacting our DNA or mitochondria!
Blue light, or UV light, are very short wavelengths and influence our health at the level of our skin and eyes. This has an indirect influence on our health.
It is this full spectrum of light that has an ability to impact our health at every level. As we learn more about light’s affect on our health, we realize it’s like a sharp, precise scalpel. It’s no wonder the power of light continues to be such a highly investigated topic! Current research shows the following influences from light:
Lighting up your day: UVB / Blue light benefits (think daylight/ sunlight!)
- Activates our immune system.
- This helps explain why during the spring and summer months we get fewer colds and flus. It’s not that we’re exposed to less germs (germs are everywhere, always), it’s just that our immune system is better at deploying immune cells and combating bacteria and viruses.
- Triggers regeneration in our skin, hair, and nails.
- Ever wonder if it’s just a coincidence that hair thins during the winter months, or that hair and nails grow more quickly in the summer? This is linked to the mechanism that UVB light triggers, stimulating an increased turn over of stem cells that help produce more new and healthy cells. So, our skin, hair and nails often look more youthful and healthier during the sunnier seasons!
- Improves mood!
- One of the big struggles for us during the long winter months is that we can start to feel more down. Studies show that daylight exposure early in the day can effectively improve mood and help reduce symptoms of depression.
But with winter weather, we have less overall sunlight to enjoy, and we tend to really restrict our time outdoors due to the temperature and conditions.
Fear not. There is something you can do. Here are three tips to incorporate some daylight therapy into your daily routine:
- Open your blinds right when you wake up!
- Enjoy your breakfast/ coffee beside a window, or even better, outside in the sunlight.
- Go outdoors soon after waking. Enjoy a walk to get your coffee/ or with your coffee, walk to work, or exercise outdoors for 30-60 minutes.
When the above options don’t work, there are alternate solutions such as indoor sunlight lamps. Studies show that 10,000 lux for 30 minutes first thing in the morning can improve mood. Examples of lamps are here and here.
Timing is key. Blue light delivers its benefits to us when used in the daytime coinciding with our body’s evolution with the sun cycle. On the flip side, blue light at night can impair us.
UVB/ Blue light at night impairments:
- Inversely affects mood, so being exposed to this kind of lighting, via artificial lights at night, can increase depression and mood disruption.
- Increased heart rate, meaning that our stress state stays overly active and impairs our ability to relax.
- It reduces our heart rate variability (lower HRV means we have lower resilience to stress and poorer cardiovascular fitness; we want to aim for a higher HRV!).
- Impairs our metabolism.
- Makes us wake up with insulin resistance meaning we start the day with impaired, less than ideal blood sugar levels, making weight loss goals more difficult to achieve.
- Dissipates melatonin.
Melatonin is our hormone of darkness. Darkness is its cue to be released into our system. It is what orchestrates the components needed to initiate and sustain quality sleep. But when we are exposed to blue light, our melatonin levels can drop to near zero which is not ideal.
Our bodies have adapted to the times of the year when there is less sunlight. We naturally have more melatonin during these months. Yes, our bodies have evolved to benefit from seasonal changes of light as well which is pretty cool! Our bodies are way smarter than we often give them credit for. With more melatonin we feel sleepy more often and spend more time in bed, which is not necessarily a bad thing! Sleep is the ultimate underlying foundation for good health and all health goals such as those described with light exposure, immune function, healthier organs, and proper function of all physical and mental elements improve with better quality and quantity of sleep. Melatonin is also a potent antioxidant and anti-cancer molecule, so those longer cozy, dimmer evenings can be a powerful way to protect our health as well.
Your big takeaway to using light therapy in your evenings is to avoid blue light at night. Specifically, studies show that ideally refraining from blue light between 10pm-4am is ideal. If you must have your laptop on to do work or use a screen consider these tools to minimize the damage:
- Instal f.lux
- Use your night shift mode on your phone
- Put on blue light blocking glasses (never wear blue light blocking glasses during the day, as this prevents you from reaping the benefits of daytime light exposure described above)
By understanding and appreciating how light and darkness impact our health we can utilize this powerful cue from our environment to support us. Our biology is wired to work in sync with these light and dark cycles that are all around us. If you are feeling out of sync, that’s OK! Our modern environment is not conducive to this natural rhythm. Pick just one action to practice and integrate into either your morning or evening routine. Choose the path of least resistance, and one that seems enjoyable to you, and then build from there!
References:
Panda, S. (2018). The circadian code: lose weight, supercharge your energy, and transform your health from morning to midnight. Rodale Books.
Winter, C. W. (2017). The sleep solution: why your sleep is broken and how to fix it. Penguin Random House LLC.
Huberman, A. (2022). Using light (sunlight, blue light & red light) to optimize health. Retreived from https://hubermanlab.com/using-light-sunlight-blue-light-and-red-light-to-opt