In 2001 a new class of cells were discovered in the retina of the human eye, classified as ‘circadian’ rather than visual receptors. That discovery renewed research into the spectrum, intensity and duration of light that influences psychological and biological responses. But you don’t have to be a scientist to know shift work is murder or a bad night’s sleep wrecks you the next day.
So what it is – is – that part of the physiology of the human brain, functions on what is termed circadian rhythms – in essence that rhythm is a 24hr cycle with the ebb and flow of periods of alertness and drowsiness.. The neurochemicals that dictate when we are at our maximum capacity for concentration and action or when we are ready to hit the hay are modulated by external cues such as exposure to sunlight and also temperature. It is why we wake and work best in daytime and sleep most restfully at night.
The modern world with 24hr everything, with artificial lighting even in daylight is messing about with those cues and unfortunately out-of-phase circadian rhythm is quite a health hazard – contributing to instances of fatigue, insomnia, depression and tumoral diseases alongside cardiac disease, diabetes and even obesity – as we eat out of sync and supplement our systems with coffee and sugary snack to try and keep pace. There is a lot of research about night workers and cancer and the detrimental effects of florescent lights and poor quality daytime sleep.
Gardeners garden in daylight; we reset our circadian rhythms to natures clock every time we fetch the spade or watering can. Those few hours in the morning prime us for a day of action and the evening’s light sets us up to enter a phase of rest.
The science of it is that in the brain alpha waves boost energy and detla waves suppress energy and promote sleepiness. The blue wavelengths of daylight actually suppress the drowsing delta brainwaves and boost the alpha wavelengths, so exposure to real daylight promotes cognitive function and alertness and later restful regenerating sleep – remember that sleep is the body recharging but sleep is also the body at repair – on a cellular level. Sleep is anti-aging and restorative, sleep is part of our immune and defence mechanisms.
But there is more than energy in daylight there is vitamin d. Vitamin D, which has a role in bone and muscle strength is produced in the skin from exposure to sunlight. 15minutes of sun a day is enough for most to get their daily requirement without searching out fortified cereals and super milks. People with low levels of vit d are more prone to develop osteoporosis, heart disease, hypertension, chronic fatigue, inflammatory diseases and chronic pain, certain cancers, autoimmune diseases and depression.
So yes gardeners need to protect against sun damage but a healthy dose not only promotes a sense of well-being it generates it. eating tomatoes can boost the spf of our skin so most GIYers are getting some nutritional sunblock naturally. The vit d from sun will improve sleep, reduces inflammation, strengthen bones and muscle and elevate mood. There are many trials running currently on vitamin d as a therapy for post chemotherapy recovery and for seasonal affected disorder.
all in a bit of gardening does you the power of good.
I will be talking more on this at the giy gathering sunday along with a whole shower of other know it alls – http://www.giyinternational.org/pages/the_gathering_2013 and thousands of everyday experts – the GIY membership.