Daylight is vital to physical and psychological wellbeing in many ways. Here are just a few.
Sunlight on your skin produces Vitamin D – the vitamin your body needs to absorb calcium. Calcium is necessary for strong healthy bones and lack of calcium is a major factor in the development of osteoporosis. Vitamin D deficiency has also been linked to several cancers and one study showed that Vitamin D supplements for postmenopausal women reduced the chance of getting any cancer by 60%. Now, we do need to be sceptical about such claims made by researchers and about claims for taking vitamin supplements. But, with the other benefits of daylight exposure described below, we should all prescribe ourselves a daily dose of daylight to boost our Vitamin D levels.
In my blog post on our edition of Heath Robinson’s How to Make a Garden Grow I describe the concerns about the health of the nation in the 1920s and 1930s. Many of the working class recruited as soldiers for fighting in the First World War didn’t not meet the health requirements. Rickets is also caused by Vitamin D deficiency and many children who lived in slum housing at the beginning of the twentieth century didn’t get enough daylight or enough Vitamin D in their diet for healthy bone growth. At the time there was a lot of talk about fresh air and exercise. What they didn’t know then but we do know now is that it was the lack of daylight that was largely the cause of many of the health problems identified during and after the First World War. The relationship between light and health is also covered in my blog post on How to Live in a Flat by Heath Robinson and we see the impact of these concerns on the design of housing in the early twentieth century.
Our sleep patterns are regulated by the hormone melatonin. The blue light part of the daylight spectrum enters the eye and sends a message along the optic nerve to the gland that produces melatonin. While blue light is entering our eyes, the amount of melatonin produced is suppressed and we feel awake. When it gets dark and the amount of blue light entering the eye is reduced, the amount of melatonin produced increases, we feel sleepy and our body prepares for sleep.
There is a very interesting article about blue light on this website http://moreintelligentlife.co.uk/content/features/rosie-blau/light-and-health?page=full I quote one particularly interesting section from this article, relating to the work of Kazuo Tsubota, professor of ophthalmology at Keio University School of Medicine in Japan:
Tsubota’s ambition as an ophthalmologist is “to protect the eye for this long-lived society”. We all know that our eyesight fades with age—what he calls “the eye as a camera”—but “the eye as a clock” does too. As we get older, our lens yellows, so less light reaches the receptor at the back of the eye to tell our brains what time it is—and we need more daytime rays to reset our body clock. “At 58 years, my lens is a third as good at receiving blue light as the 20-year-old lens,” says Tsubota, who talks with a wide smile and waving hands. “In order to have a proper amount of light, I have to play outside three times as much as a 20-year-old boy,” he says and laughs. “That gives me a good excuse to ski, go swimming, jogging.”
Tsubota says he is motivated by gokigen, meaning a life filled with happiness. This is not idle chat, he insists. Happiness is one of three things that help to stave off the depredations of age, along with diet and exercise. His remedy is not to sing and laugh, or even to get rich or get married, but to sleep: “It has almost the same beneficial effect on health as smoking has a bad one.” And getting a good night depends on having the right amount of light at the right time of day.
Much of his research focuses on his own cataract patients. After a cataract operation, people usually have fewer falls, their mood lifts and they think more sharply. Tsubota also found that his patients’ sleep “dramatically improved”. He believes many of the other benefits of the operation flow from this: “The surgery replaces the opaque lens and suddenly 90% of the blue light is received, you are like a five-year-old. So cataract is a treatment for the clock as well as the camera.”
The relationship between sleep and wellbeing is now well-known. However, I find this quotation fascinating for the insight it gives into the interrelationship between eye health, light, sleep and wellbeing. But, in simple terms, the equation is: more daylight = better sleep = health and wellbeing.
You may also notice another thread running through several of my blog posts – my references to Japanese philosophy such as Wabi Sabi and, here, gokigen. The Japanese are famously long-lived and are healthier for longer so they are able to add years to their lives and life to their years. Their diet is often given as the reason for this but I think there are other factors too, connected with their way of living.
We also know that quality sleep and physical health improve our psychological wellbeing. But daylight itself improves our feelings of wellbeing and quite a lot of research is now being done into the reasons why this is the case. Much of this research is collated in the following literature review http://www.nrel.gov/docs/fy02osti/30769.pdf This is a long read so, again, I will quote the section that struck me particularly:
Humans are affected both psychologically and physiologically by the different spectrums provided by the various types of light. These effects are the less quantifiable and easily overlooked benefits of daylighting. Daylighting has been associated with improved mood, enhanced morale, lower fatigue, and reduced eyestrain. One of the important psychological aspects from daylighting is meeting a need for contact with the outside living environment (Robbins 1986). According to Dr. Ott (Ott Biolight Systems, Inc. 1997a), the body uses light as a nutrient for metabolic processes similar to water or food. Natural light stimulates essential biological functions in the brain and is divided into colors that are vital to our health. On a cloudy day or under poor lighting conditions, the inability to perceive the colors from light can affect our mood and energy level. Dr. Liberman (1994) also mentioned that light plays a role in maintaining health: When we speak about health, balance, and physiological regulation, we are referring to the function of the body’s major health keepers; the nervous system and the endocrine system. These major control centers of the body are directly stimulated and regulated by light, to an extent far beyond what modern science…has been willing to accept.
We know that being outside in the sunshine makes us feel good – we don’t need research to tell us that. What the research is beginning to confirm is that it is exposure to daylight that is the reason why we feel good.
Recipe for the daylight part of our Mediterranean diet
Hang on, you may say, we are constantly being warned about spending too long in the sun, risking skin cancer, cataracts, wrinkles, etc. How do we get more daylight without incurring all these risks? Well, here is the Words to the Wise recipe for your daylight diet:
- Take a 20-minute walk every morning (even in winter – in fact, especially in winter) and expose as much skin to the daylight as is decent and without getting frostbite! You only need a 15-minute exposure to create enough Vitamin D for the day and walking in the morning means you are not exposed to strong mid-day sunlight that will damage your skin. A morning walk will also help to wake you up as the blue light will start the reduction in melatonin levels. Older Chinese people who start the day with Tai Chi outside have the right idea – gentle exercise in daylight (not artificial light) will help you to live longer, be healthier and feel good.
- For the rest of the day, take every opportunity to get some daylight. If you can’t go outside then sit near a window. Keep windows clean and open the curtains as soon as you get up. At work insist on your ‘right to light’ – show your employer the literature review I refer to above. I am sure he or she will be keen to improve productivity!
- In the evening turn off all screens (TV, tablet, mobile phone, etc.) at least two hours before you go to bed. Screens emit blue light and this will continue to suppress melatonin levels, which will make it harder to get to sleep. Make sure your bedroom is as dark as possible.
Add this recipe to your vegetables, olive oil, nuts and fruit to get the full benefit of the Mediterranean diet.
There is a lovely quotation that accompanies the Filippo Palizzi painting above:
Sul bordo dello scoglio vi è una scritta: Egli, che mi pose a giacere su questa roccia, mi dice di guardarti da mattina a sera e dirti sempre: sii felice. Felice.
On the edge of the cliff there is an inscription: He placed me to lie on this rock, tells me to look at you from morning to night and tell you: be happy. Happy.
P.S.: Our Photography books are all about capturing and recording light. Photography also gets you outside for your daily dose of daylight. Our first title on Developing a Photographic Style by David Penprase has just been published. For more information about our Photography titles visit www.RHEMediaPhotography.co.uk