Circadian Biology And Light
The way you use light can affect your health
There has been explosion in the amount of research into light, both natural light and artificial light and its effect on physiology and health.
The research comes from various areas including myopia control, chronobiology, photobiomodulation, circadian dysfunction, delayed sleep wake phase disorder, mental health, cardiovascular, vitamin D and auto immunity to name a few.
An assumption has been made that living indoors under artificial light and disregarding daily and seasonal light patterns does not come at a cost to your health. Another assumption being made via the successful “slip, slop, slap and wrap” campaigns is that any amount of direct sunlight exposure is bad for you. Can you suffer from a lack of good light?
Obviously, there is a fine line and balance between the harms and benefits of sun exposure as described by the Cancer Council Australia. Energy from the sun is expressed as the visible light spectrum as well as the non visible such as UVA, UVB and infra red light.
This is not only discussed in the context about the benefits and dangers of UV radiation, but the dual action of light is also noted in the debate about the potential benefits and dangers of blue light. Time of day matters!
This is a complex area and it is important to talk to your health care practitioner for specific advice. Light absorption depends on your age, skin colour, metabolism, latitude, the amount of exposure and the time of day.
Shift work has been linked to various health conditions over the years and it does not take much artificial light at night to affect melatonin levels in some individuals (Phillips 2019).
NB: Light therapy and/or natural light exposure is not a replacement for any medical, pharmacological treatment or lifestyle recommendation as directed from your personal physician.
Cancer Council Australia – National Cancer Control Policy
Position statement – Sun exposure and vitamin D – risks and benefits
Advances In Experimental Medicine & Biology 2008
Sunlight, UV-radiation, vitamin D and skin cancer: how much sunlight do we need?
Mifeature 2019 December
Author: Professor Ian G Morgan, Dr Amanda N French and Professor Kathryn A Rose
Myopia: Aetiology and Implications for Clinical Practice
Journal Of Internal Medicine. 2019 August
The Circadian Syndrome: is the Metabolic Syndrome and much more!
Neuroscience And Behavioural Reviews. 2020 March
New insights on the role of the retina in diagnostic and therapeutic strategies in major depressive disorder.
Physiology & Behaviour. 2019 January
Randomized trial of polychromatic blue-enriched light for circadian phase shifting, melatonin suppression, and alerting responses.
Procedings Of The National Academy Of Sciences USA. 2019 June
High sensitivity and interindividual variability in the response of the human circadian system to evening light.
Scientific Reports. 2019 March
The Impact of Shift Work on Sleep, Alertness and Performance in Healthcare Workers.