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The importance of the right light, at the right time, for health & wellbeing

Writer's picture: HelenHelen

We were born to this planet, and we rely on this planet for our survival.  No one would dispute the fact that in order to survive on earth we rely on air to breathe, gravity to stay on the ground, water to make up our body composition, and food to provide energy. 


We also rely very heavily on light. Light not only allows us to see, but exposure to light has a huge influence on our physiological and psychological functioning.  Despite its crucial role in our life, light is often overlooked as a major contributor to health and wellbeing.


Natural light/daylight


Natural light may appear white, but it is actually made up of multiple wavelengths of light: red, orange, yellow, green, blue, indigo, and violet (these various wavelengths can be seen by the naked eye through a prism, droplet of water, rainbow). Further wavelengths of light exist but we can’t see them, for example infrared is invisible to us but makes up over half of the solar radiation reaching earth and, along with UV, is absolutely critical to our body.


Human bodies absorb light particles called photons and transform this light energy into adenosine triphosphate (ATP) which provides energy to the body cells.  Different wavelengths of light have been found to have different uses in the body  –  red light is absorbed by the red blood cells, UV helps the body produce vit D,  infrared light supports cellular function. Our bodies rely on receiving the full spectrum of light, provided by sunlight, in order to function properly. 


Some researchers have argued that light is so integral to the functioning of the body that we actually make it ourselves, with all human cells emitting their own form of light . During their work in the 1970’s Popps and his team of researchers found that human cells release ultra weak emissions of light (biophotons) that are invisible to the naked eye. These biophotons are created during the thousands of chemical reactions that are happening inside a cell every second, and are used by the body to send and receive messages faster than the speed of light.  It has since been argued that these biophotons ‘appear to be responsible, at the highest operational levels of our bodies, for governing our overall biological systems’ (PRL, 2022).  


Not only do humans need light, we are light.


Sunlight is needed by almost all processes in the body – from bone health to wound healing - but there are three main systems that use light:


  1. Vision for helping us navigate the world

  2. Skin – the skin is not just a passive covering of the body.  It uses light to create vitamin D and other compounds.  It is also a self regulating protective barrier organ, which absorbs UV light in order to create chemical, hormonal, and neural signals that maintain homeostasis inside the body.

  3. Circadian rhythm regulation

 

The circadian rhythm


Circadian rhythms are critical to our overall functioning, and are essentially the body’s internal clock that regulates the physical, mental, and behavioural changes occurring over a rough 24 hour cycle (often 24 hrs and 15 minutes).


Human circadian rhythms control most of the body mechanisms including the sleep wake cycle, hormone secretion, cellular function, and gene expression.  Circadian rhythms influence our health and their disruption leads to all kinds of issues including cancer, metabolic dysfunction, and psychiatric disorders.  Severe circadian disruption, such as that seen in shift workers, has been shown to alter the structure of the brain.


Circadian rhythms are controlled by several cues or ‘Zeitgebers’ from the environment such as temperature, exercise, and mealtimes, but by far the biggest influencer of the circadian rhythm is light exposure.


Visible light enters the eyes and travels to a biological clock in the brain known as the suprachiasmatic nuclei (SCN). The SCN then generates the necessary circadian rhythms that drive daily patterns of hormone concentrations such as insulin, glucagon, corticosterone, and enzymes such as those involved in lipid and glucose metabolism. The SCN drives fluctuations in activity, food and water intake, sexual behaviour, body temperature, and hormone release that keep the body in a state of balance or homeostasis.


Artificial light


Artificial light is not the same as natural light because it does not provide the full spectrum of light required by the body, nor the nuances and fluctuations of light across the day required by the SCN to accurately drive circadian rhythms. Light from energy efficient lightbulbs, street lights, overhead lights, and screens is skewed heavily towards blue light. Of all the colours on the spectrum, blue light has the strongest effect on circadian rhythms and thus has the greatest potential to disrupt them.


In nature, transitions between light and dark tend to be gradual and consistent. Each morning when we wake up, light travels into the eyes to tell the brain to slowly rouse our body systems, and each dusk the light tells the brain to begin to prepare us for sleep. Light detection systems in the eyes are so advanced they can detect variations in the amount and wavelength of light across the day, as well as the angle of light to tell the SCN when it is sunrise versus sunset.  Energy from normal sunlight is also absorbed through the skin, and our bodies are full of light sensitive ‘switches’ that tell our body how to respond moment to moment.


In contrast, artificial light alters our light environment with the flick of a switch. We can shift from the darkness of midnight to ‘noon in June’, and then back again in a matter of milliseconds. This kind of light exposure wreaks havoc with our circadian rhythm and therefore our body functioning.


The modern light problem


Many people are spending most of their time indoors with little exposure to natural light during the day, and excessive levels of artificial blue light at night.  We have become a species that self-selects our light-dark cycles, rather than a species that follows the light-dark cycles of our natural environment. As a consequence we are disrupting the natural rhythms of our body, and sacrificing our health.


Some of the issues with blue light include:


  • Blue light first thing in the morning tells the body that its ‘noon in June’, when in fact it’s probably more like 6am in December. This disrupts the circadian rhythm and the cascade of body responses before we’ve even made it to the bathroom.

  • Exposure to continuous artificial light from waking until sleeping prevents the SCN knowing what time of day it is and regulating the body systems accordingly.

  • Blue light is evidenced to damage both eyes (photoreceptor damage) and skin

  • Blue light at night has been shown to increase cortisol (stress hormone) levels, which contributes to inflammation, weight gain, high blood pressure, and other health issues.

  • Blue light influences insulin resistance (where the body cells do not respond effectively to insulin) leading to elevated blood sugar levels and risk of type 2 diabetes.

  • Blue light stimulates dopamine, which in high levels can impact mental health and is linked to several psychiatric disorders such as depression and psychosis. Blue light via screen use may be particularly problematic for dopamine levels, as blue light from the screen is coupled with artificial dopamine spikes that come from quick fix social media likes, and binge watching Netflix (genuine dopamine boosting activities include things like exercise, social connection, hobbies, achieving goals)

  • Blue light disrupts melatonin production which has its own catalogue of heath consequences


Melatonin


Melatonin is an important hormone moderated by the circadian rhythm and SCN. It’s often known as the sleep hormone as it is released towards bedtime and throughout the night. When exposed to light during the day, our body suppresses melatonin production, making us feel alert.  When it is dark, our body turns on melatonin production which makes us feel drowsy. 


Melatonin generally starts to be released by the pineal gland when the SCN detects the changes in light associated with sunset (typically red orange and yellow). If we do not receive natural light, and instead expose ourselves to artificial blue light during this time we disrupt the natural rise of melatonin.  This makes it harder for us to get to get to sleep, to reach the stages of deep sleep, and to stay asleep throughout the night (3-4am waking is quite typical with blue light exposure).  


In addition, regular suppression of melatonin does more than just impact our sleep.  Melatonin is one of the most powerful hormones in our bodies and low levels have been linked to a large variety of health issues. For example:


  • Melatonin interacts with female hormones and helps regulate the menstrual and reproductive systems.  Female hormones are heavily dependent on the 24 hr cycle and many studies have therefore examined the role of light upon female hormone production. There is evidence of a relationship between light exposure, melatonin secretion, and irregular menstrual cycles, menstrual cycle symptoms, and disordered ovary function

  • Melatonin protects against neurodegeneration which is often present in Alzheimer’s and Parkinson’s disease.

  • Low melatonin is linked with anxiety and mood disorders

  • Low levels of melatonin are linked to immune suppression, with higher levels shown to inhibit the growth of certain cancers


The solution


There is no easy solution to a world that bombards us with the wrong kind of light at the wrong time of day every single day, unless you fancy returning to the wild (very tempting in my case).


However I have noticed that for almost all of my clients, light exposure is a issue that is impacting their mental and physical health, primarily because it disrupts their sleep patterns and creates excess stress within the body.  Light exposure is therefore often one of the first things we discuss, and almost everyone starts to feel at least a little better with improved sleep. 


Things I suggest, and that I practice myself include:


1.        ‘Sun before screen’.  Do not have your phone in your room.  Buy a basic alarm clock (make sure it doesn't emit blue light, as many do) and leave the phone outside the bedroom so that you are not tempted to look at it when you wake up.  Try and ensure you get sunlight in the eyes and on the skin first thing.  This is hard in winter when the sun rises 2 hours after you do, but try and get sunlight into the eyes as early as possible regardless.

 

I commonly suggest people get up and do a series of sun salutes first thing to both break the habit of reaching for the phone, and to start the day with movement and breath (which regulates the body) rather than a screen (which dysregulates it).

 

As tempting as it is, never look at your phone to check the time or scroll in the middle of the night.  A quick flash of blue light at 2am will stop melatonin production and you’ll find yourself wide awake, and your SCN very confused.

 

2.       Increase your exposure to natural daylight; as much as you can as often as you can. Although midday sunlight does contain blue light, it is balanced with other colours and is therefore different to the blue light of screens and bulbs.  As far as possible, rely on daylight rather than artificial lights during the day.  Turn off the office lights, open the blinds. Outdoor light ranges between 1000 lux at sunrise/sunset and on a cloudy day, and 100,000 lux + in the middle of a sunny day.  Artificial light levels are usually around 50-100 lux at home and 100-500 lux in the office.  Research indicates that 1000 lux is needed for proper melatonin suppression during the day, and artificial lights get nowhere near this level.

 

Glass absorbs some rays of light especially the important UV waves, so I often open the window nearest to me when I’m getting ready in the morning, and open the car window when I’m driving in order to let the light in. 


Get outside and go for a walk. Take off the sunglasses.  Make being outside a non-negotiable daily habit. Sit in the park for 15 mins between meetings, stare at the horizon rather than a screen whilst waiting for your appointment,  If possible repeat the process of getting light in the eyes at sunset, so the SCN gets accurate information about the time of day.  Try and be consistent with your light exposure daily in order to support circadian regulation.

 

3.       Reduce screen time, especially at night and especially in the few hours leading up to bedtime.  Easier said than done I know, but it’s necessary, not optional, for health.


It’s important to note that for some people, reducing screen time is not only difficult but also scary.  Screen use is often not just a habit, but may be a way that a person has found to manage their emotional states and deal with loneliness, loss, sadness, stress, anxiety, and emotional strain.  Screens are frequently used to distract, deny, and avoid difficult issues (in much the same way as alcohol and other addictions), and reducing screen use may therefore need to involve deeper work to address underlying concerns.

 

4.       If you have to use a screen, consider investing in blue light blocking glasses. You can buy glasses that block blue light all day for those that work on screens, and others that are just designed for evening use.  There are all manner of blue light blocking options available on the market.

 

5.       Reduce light at night.  Aside from screens, assess the lighting in your home and the impact this may be having.  I do not use overhead lights in my home in the evening, I use side lamps placed at a low level.  It is now possible to buy blue light blocking bulbs as well as bulbs that emit the same spectrum of light as daylight (although these are expensive compared to standard bulbs).

 

I believe spot lights are a health disaster and I genuinely don't understand why they are typically placed in bathrooms, meaning that the last thing we do before bed whilst we brush our teeth is blast our eyes with bright light from above. I use freestanding night lights (non blue light) in my bathrooms and leave the spots off.

 

When I teach evening yoga classes I use warm coloured fairy lights on the floor. This is just enough light to see, but its warm and low so slightly more typical of sunset – you could apply this idea to your home or bedroom.

 

As a final thought, there are some researchers who believe blue light is the modern day version of smoking. Back in the 1950’s scientists found that the chemicals in tobacco caused cancer, but the cigarette companies buried these studies and promoted smoking with the aim of creating addiction, purely for their profits.


Screens are addictive, blue light is damaging. Research is increasingly showing both of these to be true, however I’m quite sure there is more evidence being buried. It may therefore be time to consider how much blue light we wish to consume.

 

Sources:


Danilenko KV, Sergeeva OY. Immediate effect of blue-enhanced light on reproductive hormones in women. Neuro Endocrinol Lett. 2015;36(1):84-90. PMID: 25789589.


Danilenko KV, Samoilova EA. Stimulatory effect of morning bright light on reproductive hormones and ovulation: results of a controlled crossover trial. PLoS Clin Trials. 2007 Feb 9;2(2):e7. doi: 10.1371/journal.pctr.0020007. PMID: 17290302; PMCID: PMC1851732.


Shadab A Rahman, Leilah K Grant, Joshua J Gooley, Shantha M W Rajaratnam, Charles A Czeisler, Steven W Lockley, Endogenous Circadian Regulation of Female Reproductive Hormones, The Journal of Clinical Endocrinology & Metabolism, Volume 104, Issue 12, December 2019, Pages 6049–6059, https://doi.org/10.1210/jc.2019-00803


Lee Barron M. Light Exposure, Melatonin Secretion, and Menstrual Cycle Parameters: An Integrative Review. Biological Research For Nursing. 2007;9(1):49-69. doi:10.1177/1099800407303337


Slominski AT, Zmijewski MA, Plonka PM, Szaflarski JP, Paus R. How UV Light Touches the Brain and Endocrine System Through Skin, and Why. Endocrinology. 2018 May 1;159(5):1992-2007. doi: 10.1210/en.2017-03230. PMID: 29546369; PMCID: PMC5905393.


Petrowski K, Buehrer S, Niedling M, Schmalbach B. The effects of light exposure on the cortisol stress response in human males. Stress. 2021 Jan;24(1):29-35. doi: 10.1080/10253890.2020.1741543. Epub 2020 Apr 6. PMID: 32160826.


Tosini G, Ferguson I, Tsubota K. Effects of blue light on the circadian system and eye physiology. Mol Vis. 2016 Jan 24;22:61-72. PMID: 26900325; PMCID: PMC4734149.


Kumari J, Das K, Babaei M, Rokni GR, Goldust M. The impact of blue light and digital screens on the skin. J Cosmet Dermatol. 2023 Apr;22(4):1185-1190. doi: 10.1111/jocd.15576. Epub 2023 Jan 3. PMID: 36594795.




The Brains Way of Healing. Stories of remarkable recoveries and discoveries. Norman Doidge (2016)

 

 



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