Artificial light: How man-made brightness has changed the way we live and see forever

Before the advent of artificial light, humans had to go to bed when the sun went down.

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Our modern lives would be inconceivable without abundant, cheap electric light, which for more than a century has illuminated homes, streets, workplaces, restaurants, theatres, and stores, extending both our work and our leisure time. And although the illuminated city, and the glamour and liveliness of its nights, has come to define what it means to be urban and urbane, most of us almost never think about light, since however much of it we desire – often more than we need – is usually readily available at the flick of a switch.

This thoughtlessness, and the freedom light grants us, is something humans couldn't dream of even a few hundred years ago. In the late 18th century, lamps were still rudimentary, depending on the same technology that had illuminated Roman homes and even the caves of the Pleistocene: a vessel – of stone, clay, or metal – with some kind of animal or vegetable fat as fuel, and a wick. Except for the very wealthy, or for those living in places where fuel might be abundant, light was precious and used sparingly, in part because all fuel for light could also be used for food. John Smeaton, in his account of building the Eddystone Lighthouse off the coast of Plymouth, wrote that he "found it a matter of complaint through the country – that the light keepers had at various times been reduced to the necessity of eating the candles".

All light had to be tended continually. It stank and it smoked. And the open flame was always a danger. Countless conflagrations were caused by a tipped-over candle or lamp, so much so that in some medieval cities residents were required to put out their cooking fires – often the only interior light many could afford – after dinner. "Curfew" comes from the Old French couvre-feu, meaning "cover fire".

Not only households were dark. In the Middle Ages there would have been no street lighting and, with only the volunteer night watch to keep guard, the authorities – so as to keep civil order – required residents to stay in their homes after dark. Most willingly obliged. Not only would any night traveller be in danger of tripping over woodpiles and stones, or of falling into a river, but there were plenty of footpads and thieves on the roam.

During the late 17th century, the dark of the city streets gradually began to recede. At first, citizens in some districts were required to keep lit candles on their street-facing sills during the dark of the moon. These were eventually replaced by streetlamps funded and maintained by municipalities, and paid for by taxes. The times set for lighting the lanterns – fuelled by oil, tended to by lamplighters – varied with the seasons and the phases of the moon, and the light they gave was dim and uneven.

Although oil streetlamps did begin to open up the city evenings, the confinement of the dark nights would truly begin to lift in the 19th century. Not only did brighter, cleaner mineral fuels – such as kerosene (or paraffin) – begin to replace whale oil and tallow, but the story of human light ceased to be that of lamps and candles alone.

Gaslight arrived in the early 19th century, first in the wealthier residential and commercial districts of London. Gas, then, was a by-product of coal, and a system of pipes linked large gasworks and storage tanks to customers. The interconnected system meant the brilliance of a neighbourhood lit by gas increased exponentially, and gas brought more than brilliance. This interconnectedness meant people gave up control of their light to an outside interest, and their homes were connected to their neighbours' homes, to the homes of strangers, to factories, and to the streets, in a shared fate. Light's abstract future had begun: there was nothing to tend, no wick to see consumed, no melting wax or reservoirs of oil drawing down. The flame not only stood upright but shot out of the core sideways or upside down, in the shape of a fish tail, a bat wing, or a fan. It was not to be doused with water or extinguished with breath.

Gaslight proved to be popular and spread quickly to even modest British cities. By the mid-19th century, gaslight illuminated Paris, New York, and other major cities throughout Europe and the United States. A burgeoning middle class took advantage of the extended hours of light to window-shop, and to frequent theatres, taverns, and restaurants. The cities, which for so long had largely functioned by daylight alone, were now known by their nights: "During the day, often sober; in the evening, more buoyant when the gas flames glow," Karl Gutzkow of Paris wrote. Perhaps most tellingly, "nightlife" is a 19th-century word.

By the middle of the century, the streets had also begun to be illuminated by electric arc lighting, a technology first successfully demonstrated in 1809 by Humphry Davy at the Royal Society of London. But arc lighting was far too brilliant to be used indoors, and the search for a practical, modest electric light for homes and businesses occupied many experimenters throughout Europe, Russia, and the US for much of the 19th century. Thomas Edison joined the fray quite late, in 1878. In his Menlo Park, New Jersey laboratory he contracted mathematicians, blacksmiths, machinists, model-makers, and glass-blowers to develop not only the incandescent bulb but the system to support it. Edison was able to display an electric light to the public in late 1879.

This new light first illuminated factories, commercial districts, and the homes of the wealthy. It remained a luxury for most home owners until electric lines began to arrive in middle-class and working-class neighbourhoods during the first decades of the 20th century. The last to receive electricity were usually those who lived in poorer city neighbourhoods or in the countryside. By the time it arrived in American farmhouses in the 1930s – generally lit until then by dim kerosene lanterns – incandescent light couldn't really be separated from all the other things that electricity brought into the home: refrigerators, washers, dryers, irons, stoves, vacuum cleaners. It seemed to define what it meant to be modern. And although all these other things would dramatically change domestic life, somehow it was the light people were waiting for.

The rapid expansion of power grids throughout the 20th century means those in industrialised countries now live in a world built of light, but the light that affords us an ease and freedom our ancestors couldn't imagine also has consequences. It has so effectively chased away the ancient night that more than half the people in the United States and Europe cannot see the Milky Way from their homes. Astronomers were the first to raise an alarm concerning light pollution, calling for better-designed lighting and an end to excessive lighting, which not only obscures the night sky but has consequences for our well-being – it affects human sleep, among other things – and can wreak havoc in the natural world by disrupting the migration of birds, for instance, that depend on celestial light to navigate, and affecting the ability of nocturnal animals to hunt and hide.

Only a conscientious effort to reduce lighting will ensure a future in which the brilliance we live by even remains the same, for our reaction to light isn't always rational. Not only do we love its beauty and ease, we imagine it makes us safer in the night, though safety may not always be a function of more light: blinding glare can give advantages to modern-day footpads and thieves, and light itself can help them to navigate their way.

At the moment, as part of the drive towards energy-efficiency, we find ourselves in a new age of experimentation and innovation in lighting: the search is on for better compact fluorescent lighting, innovative LED lighting, and more efficient incandescent lighting. These new technologies may also help the third of the world who still live out of reach of a power grid to gain some of the advantages of the well-lit night while sidestepping its liabilities. For those in the industrialised world, technology won't solve the problems of light pollution entirely. The well-lit future will also require a reimagining of the way we think of light, as we ponder the possibility that we might be hampered by the very brilliance that has made us who we are.

'Brilliant: The Evolution of Artificial Light' by Jane Brox is published by Souvenir Press (£18). To order a copy (free P&P), call Independent Books Direct on 08430 600 030, or visit www.independentbooksdirect.co.uk.