Strengthen Circadian Rhythms & Increase Energy with Light
Circadian rhythms in our body govern the timing of various processes within the 24 hour cycle of a day. For example, through the natural release of cortisol and adrenaline to help wake you and melatonin to help you sleep, as well as processes such as cell repair and digestion. Anything we do to strengthen these processes will both boost our physical health and energy, through having proper hormone release, nutrient release, healthy organs, and regular sleep/wake cycles.
There are several factors we can influence to strengthen circadian rhythm, such waking and sleeping time and consistency, light intake into our eyes, when we eat and when we exercise. Of these, light is one that is easy to forget, however many scientists, including Dr Andrew Huberman note it as the most powerful. This post will briefly explore the impact of light on your life in ways you may not be aware, and how to gather data and implement tools to improve mood, health, and maybe even live longer.
LIGHT
The eye essentially is an extension of the brain and the only part that sits outside the skull, showing the importance of receiving light signals directly to it. However, not all light is received equally at the eyes. The key factors are explored below:
- Temperature: Light is generally stated in temperature, in a range from 1000 to 10,000 Kelvin. This is just due to the way it is measured and is directly related to wavelength. Lower temperature light tends towards red colours, and higher temperature towards blue. Blue light generally makes us more alert, more red light generally has less effect on circadian rhythms. Natural light temperature is generally lower (more red) in the evening, and higher (more blue) in the morning.
- Intensity: Light intensity for a given area is typically measured in lux, which is measured as 1 lumen over a square meter area at 1 metre from a source. 1 lux is a typical moon light at night, 100 lux is a cosey living room lighting, 1000 lux is a brightly lit hospital or being by a window on a bright day, 10,000 lux is being outside on a bright day, looking away from the sun, 100,000 lux is direct, bright sunlight. Ofcourse, always be careful to avoid bright light directly into the eyes.
- Direction: There are specific cells called intrinsically photosensitive retinal ganglion cells (ipRGCs) located towards the lower part of our retina. These are less involved with vision, and instead tell the brain whether it’s light and control circadian rhythms. Hence we can leverage the direction of light into our eyes, where light from above will have more effect (generally increase wakefulness) and light from below will have less effect.
DAILY HABITS
- Get light at a consistent time each morning: Getting light as soon as you wake not only gives the brain a circadian cue for daily internal cycles, but light also supresses melatonin, and hence will help you feel more alert quicker. I go for a 15 minute walk within 15minutes of waking each morning, which weather dependant would generally account for 1000–10,000lux. I also meditate outside to boost this where possible. When the seasons or weather does not permit, I use a SAD light, which puts out 10,000 lux throughout the morning. The period of most benefit is within 1–2 hours after waking.
- Get light at sunset: Getting light when you wake in the morning can actually shift your waking time earlier the next day, getting light later around sunset, will offset that. Also, it has been shown that getting natural light around sunset will reduce the negative effects of getting blue light later in the day, helping us fall asleep.
- Avoid light, particularly blue light from above, at night: Within 2–3 hours of your sleep time, you want to minimise all light, particularly blue light from above. Light supresses melatonin and will signal your brain to stay awake, hence keep all light minimal, low and lower, more orange in temperature.
- To give you an energy boost: Finally, viewing light through the eyes will suppress melatonin, and hence if you are feeling drowsy during the day getting safe levels of light into the eyes will help give you an energy boost.
TOOLS
- SAD lights: Where natural light is not strong enough, SAD lights are relatively inexpensive way to get high lux, blue light. I tend to work with one at my desk for the first few hours of the day in the UK winter.
- Night shift: Light shifting functions on phones, tablets, TVs etc will all help to reduce intensity and drop temperature of light exposure in the evenings. I have all my devices shift 3 hours before bed.
- No screens before bed: I personally have a rule of no screens 1–2 hours before bed and it helps keep my time to fall asleep below 10 minutes most nights. Reading before bed has become an integral part to my sleep hygiene habits.
- Low lighting: During the hours of 12–4AM the brain is particularly sensitive to light, and can even negatively affect neurotransmitter release in the form of dopamine. Using low, floor lighting, orange in temperature can help minimise lighting if it must be on at night.
- Light measurement devices: You can either take measurements on your phone through apps or purchase an all in one light measurement device from LYS. I purchased one last year, and used it to track my light exposure through the dark winter in the UK. The next article will cover this in detail.
SUMMARY
Being mindful of light intensity, temperature, direction, and timing is integral to your sleep quality, energy and mood through the day. Getting a strong exposure to blue light of 1000lux+ in the first 1–2 hours after waking both starts the circadian cycles, and promotes alertness throughout the day. Getting good light exposure in the day and around sunset (providing this is 2–3 hours before bedtime) both keeps you alert through suppressing melatonin, boosts mood, and makes evening light exposure less sensitive. Minimising all blue light, and as much light in general in the lead up to bed time both allows for faster and higher quality sleeping. Why not try experimenting with these in your own routine, to boost your health and energy in the short and long term.
As always, thank you for reading, and please share your experiences in the comments section :)
FURTHER READING:
