"From technological breakthrough to health risk epidemic" would be the historical parable of artificial light according to an article in the pages of "Nature" written by Charles Czeisler, of the Department of Sleep Medicine at Harvard Medical School.
Artificial light is one of the factors most strongly associated with sleep deprivation, a condition very common in our society and one that can lead to a number of pathological conditions which are becoming more ever more prevalent including obesity, diabetes, cardiovascular disease, depression and stroke.
Recent research in this field, conducted both on animals and humans, has shown that staying awake longer alters the expression of hundreds of genes. At the behavioural level we have seen, for example, that prolonged wakefulness causes you to eat more than the actual energy needs of the body. There are measurable effects on the immune system: to keep its balance, the body needs a sufficient number of hours of sleep per night.
Even more obvious are the effects on the mental faculties: to be most affected are the attention span, concentration and learning, and also the mood can pay the price. Moreover, lack of sleep leads to increased state of anxiety and depression that some studies have linked even to a higher rate of suicide.
About one third of adults now complain about insufficient number of hours of sleep compared to 3% fifty years ago. Children fare no better, with data showing that worldwide, children sleep on average 1.2 hours per night less than a century ago
The causes of this shift are certainly found in the move towards the production of goods and services 24 hours a day, 7 days a week, with people working longer hours and increasingly on night shifts. Of equal impact however are the voluntary and recreational activities of going out and watching TV.
In all this, the role of artificial light is rarely emphasized, but it is essential. Our ears have two functions: that of hearing and balance. Equally our eyes, in addition to the function of vision, act as transmitters. Via the ganglion cells of the retina, they send information about the presence of ambient light. And it is light which is the most important of all the signals that regulate the circadian rhythms, or our "internal clock".
Once in the brain, these signals trigger a series of different effects. They inhibit neurons that promote sleep, suppress the release of melatonin, which is important for the regulation of sleep-wake cycles from the pituitary gland, and activate neurons' orexin in the hypothalamus which promote wakefulness.
Over millennia the human being has evolved according to the circadian rhythms set by natural light. In less than a century however, artificial light has proliferated our environment to such an extent that in inhabited areas total darkness no longer exists. In other words, both we and the natural world around us are understanding night time to be day.
Moreover, the advent of low energy LED is compounding the problem as its light has a wide variety of components from the blue-green spectrum, which the ganglion cells of the retina are more sensitive to. Artificial light will continue to signal more and more that it is not time to sleep, and as increasing numbers of devices such as TVs and computer screens utilise LED technology, the problem will only get worse.
Fortunately, the mechanisms by which the artificial light suppresses sleep are now more clear, allowing us to better remedy the problem. Scientists, for example are already developing technologies which minimise the blue-green component of LED in favour of the yellow orange. Ultimately however, the best solution lies within our own grasp... Reduce the time we site in front of TV's, laptops and tablets after dark!
Article Source: http://EzineArticles.com/expert/Julian_M_Jones/2145653
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