by Richard Hobday

Kept to within reasonable limits, direct sunlight is the best thing that nature can do for our health. Some of its effects have been known for thousands of years. This makes it all the more astonishing that physicians and architects have long reacted to this knowledge with ignorance or rejection. And, all too often, this reaction remains unchanged.

Medical practice has often had a direct and very profound influence on the development of architecture; and nowhere is this more evident than in the guiding principles of the Modern Movement. The ideas which first informed Modernism were formulated at a time when the building professions were in the vanguard of a battle against tuberculosis. Throughout Europe, hundreds of thousands of people were dying each year from the `white plague’, which, although in retreat, was still taking more lives than smallpox, typhoid, scarlet fever and all the other infectious diseases of the era combined. Many of the pioneers of modern architecture were involved in the construction of tuberculosis sanatoria. They were familiar with the medicine of their day and sometimes worked alongside doctors who used sunlight to cure their patients.

In 1903, the Nobel Prize for medicine was awarded to Dr. Niels Finsen, the Danish physician and scientist who discovered that ultraviolet radiation could heal Lupus Vulgaris, a form of tuberculosis thought to be incurable. Finsen’s Nobel Prize followed the discovery by two British scientists in 1877 that the sun’s rays could kill bacteria, and could do so having passed through glass. Their work prompted other scientists to investigate the effects of exposing bacteria to the sun’s rays, and it was not long before sunlight was being hailed as `nature’s universal disinfectant’ and an important weapon in the fight against infectious diseases. Sunlit rooms were held to be hygienic, while those that did not admit the sun’s rays were not. Architects began designing hospitals with large south-facing windows to admit direct sunlight and prevent the spread of tuberculosis and other pathogens. They built terraces and balconies where patients with tuberculosis could be exposed to the sun under medical supervision, a practice which became known as heliotherapy.

During the First World War, military surgeons used the sun’s rays to disinfect and heal the wounds of casualties on both sides of the conflict. Then in 1921, medical researchers proved that sunlight could cure rickets, a crippling bone disease that had been endemic in England, and elsewhere, for nearly 300 years. The discovery of the sanitary and then the therapeutic properties of sunlight brought about by Finsen and others had a marked effect on building design from the turn of the century onwards. In his influential manifesto The Athens Charter, Le Corbusier proclaimed that:

“To bring in the sun, that is the new and the most imperative duty of the architect.”

In fact, there was nothing new about it. Throughout the ancient world, architects and engineers built for the sun. They undertook much of this work to facilitate sun worship and mark the sun’s path through the heavens. They also appreciated that sunlit buildings could prevent disease. Nearly five thousand years ago, work began on Egypt’s first pyramid; the Step Pyramid at Saqqara, near Memphis. The architect in charge was also a doctor, and the high priest of an Egyptian solar cult.

Today, Imhotep is remembered as the master-builder of one of the world’s great monuments; but he also personifies the historic link between the sun, architecture and medicine. The ancient Egyptians worshipped the sun for its healing powers and used sunlight as a medicine. The Ebers Papyrus, one of
the oldest surviving Egyptian medical texts, recommends it. Some of the most distinguished doctors in Greece, Rome and the Arabic world practised sunlight therapy. The Romans built solaria where they could sunbathe for health, and their best villas, baths and health temples were carefully oriented for the sun. Indeed, the citizens of Imperial Rome considered sun exposure so important they had right-to-sunlight legislation.

Photos: Diana Neely / Taxi / Getty Images

Eclipse and Rediscovery

However, in the years that followed the Fall of Rome, doctors attached rather less importance to sunlight, hygiene and sanitation. There is barely a reference to the sun in western medical literature until the end of the 17th century. And it was not to be until the latter part of the 19th century, following the rediscovery of the sun’s health benefits, that buildings were arranged to admit its rays again. In England, the government had introduced a Window Tax 1695, and while this tax was in force, windows were bricked up and houses were often designed with the minimum of fenestration to avoid payment. Unfortunately the tradition of inadequate windows extended well beyond the abolition of the tax in 1851. In addition, the air pollution and dismal housing that accompanied the Industrial Revolution meant that sunlight was in very short supply outside buildings as well as in them.

While legislators may have been ignorant of the relationship between sunlight and occupant well-being during this period, high levels of natural light were encouraged in hospitals by a few enlightened individuals, including Florence Nightingale, the pioneer of modern nursing. Miss Nightingale considered sunlight vital in providing a healthy environment for the sick. This was emphasised in her Notes on Hospitals of 1859 as follows:

“Direct sunlight, not only daylight, is necessary for speedy recovery, except, perhaps, in certain ophthalmic and a small number of other cases. Instances could be given, almost endless, where, in dark wards or in wards with a northern aspect, even when thoroughly warmed, or in wards with borrowed light, even when thoroughly ventilated, the sick could not by any means be made speedily to recover… All hospital buildings in this climate should be erected so that as great a surface as possible should receive direct sunlight – a rule which has been observed in several of our best hospitals, but, I am sorry to say, passed over in some of those most recently constructed. Window-blinds can always moderate the light of a light ward; but the gloom of a dark ward is irremediable… The escape of heat may be diminished by plate or double glass. But while we can generate warmth, we cannot generate daylight, or the purifying and curative effect of the sun’s rays.”

When Florence Nightingale made these observations, architects and doctors were still largely unaware of the health benefits of getting sunlight indoors. Her thinking on the subject was in advance of scientific opinion and ran counter to the prevailing orthodoxy, which was to keep patients out of direct sunlight. She believed that a view of the sky and especially sun was of the utmost importance to the sick. Something else she insisted on was fresh air, and lots of it. The air within a hospital ward had to be as pure as the air outside, without chilling the patients. Air was not fresh if it was not warmed by the sun, nor was it safe if it came from anywhere other than an open window. In the 1850s, the effect of poor ventilation on the sick and the well were not generally recognised. It was not unusual for medical staff to keep ward windows hermetically closed for fear of lowering the air temperature.

Florence Nightingale was an advocate of the pavilion system, originally a French arrangement of separate ward units. The Nightingale ward, as it became known, was extensively glazed by the standards of the day. A minimum of one large window for every two beds provided patients with copious amounts of fresh air and natural light. However, it was to be many years before her ideas gained acceptance. In 1933, the Royal Institute of British Architects published a report on sunlight penetration in buildings, in which they referred to the principles described in Notes on Hospitals, as follows:

“It is gratifying to note that some architects are at last, although half a century too late, beginning to take advantage of Florence Nightingale’s common sense…”

With the discovery that sunlight could cure rickets and tuberculosis, and that it could kill bacteria, there were good grounds for getting sunlight in and around buildings. The architectural language that Le Corbusier developed from the 1920s onwards reflects this; drawing its inspiration from the sunlit ward of the sanatorium, and the terraces of the heliotherapy clinic. His iconic Villa Savoye, built near Paris in 1929, is designed for sunbathing. The living quarters on the first floor of face into a sun terrace. This incorporates a ramp that goes up to a sunbathing enclosure on the roof, which is sheltered by a screen of straight and curved walls. Le Corbusier believed the sun conferred physical and moral regeneration on those who exposed themselves to its rays. He was a keen sunbather, and was greatly concerned about the dangers of tuberculosis. This is clear from the book he wrote in the 1950s on one of his later buildings; L’Unité d’Habitation or Marseille Block: “Doling out cosmic energy, the sun’s effects are both physical and moral, and they have been too much neglected in recent times. The results of that neglect can be seen in cemetery and sanatorium.”

L’Unité d’Habitation was the realisation of the mass housing schemes that had exercised Le Corbusier since the 1920s. He designed L’Unité to alleviate a severe post-war housing shortage in France. This milestone of modern architecture is arranged for sunlight and incorporates many of the features of a heliotherapy clinic. Balconies on both the east and west facades serve as sunscreens or ‘brise-soleil’ that shade the apartments in the summer months. They are also what Le Corbusier called an ‘open-air extension’ of each living room. In addition, L’Unité d’Habitation has a terraced roof that provides amenities for the residents, including a solarium.

The Decline of the Sun

Until the middle years of the last century, natural lighting largely determined the plan of a building and the design of its external envelope. But with the advent of low-wattage fluorescent tubes in the 1930s, and air conditioning, reflective glass and cheap energy, the urban landscape began to change. Daylight was no longer a critical design element, as these technological advances made lighting deep-plan buildings a practical proposition. Medicine was changing too. Improvements in living standards led to a decrease in tuberculosis and rickets; and the arrival of antibiotics in the 1940s meant that infectious diseases were much more amenable to treatment. This is reflected in hospital design where sunlit, airy wards came to be replaced by structures that were more complex, and were closed to the elements. Gradually, the emphasis shifted from putting hospital patients in wards that supported healing and prevented infection, to ones that created a comfortable and more convenient environment for patients and staff. Sixty years ago, it was well recognised that sunlit wards have fewer bacteria in them. Today it is not. However, strains of tuberculosis have emerged that are resistant to antibiotics, and one of the so-called `superbugs’ that infect our hospitals is becoming established in the wider community. The MRSA bacterium, or methicillin-resistant Staphylococcus aureus, has long been a serious problem in wards and nursing homes where it infects patients weakened by disease or injury. But a strain has emerged that can infect healthy young people who have had no prior hospital exposure. With drug-resistant bacteria posing an evergreater threat to public health, sunlight’s germicidal properties merit rather more attention than they receive. So too do the therapeutic properties of sunlit spaces.

Bright Light

In Greece and Rome, physicians called the emotion associated with gloom and darkness `melancholia’; and the idea that lethargy, sadness and despair can be triggered by low light levels is certainly a very ancient one. During the 1980s, scientific evidence emerged of a link between depressive illness and light deprivation. Based on this and other more recent findings, it has become clear that building occupants do not get enough bright light to have a positive impact on their health and emotional stability. The light levels required for this are much higher than those needed to perform visual tasks. Electric lighting developed under the assumption that the only significant purpose of light for humans is to see. Until recently, the impact of artificial light on physiological and psychological well-being was not generally considered.

A major breakthrough came in 2002, when scientists discovered a new sensory system in the human eye. This is not involved in vision: it is there to receive and respond to light, sending signals directly to the body’s biological clock. This clock, in turn, regulates the secretion of hormones and neurotransmitters in the brain. These have a direct influence on our health and the amount of light and darkness we expose ourselves to dictates when, and how much of them, is secreted. Although bright light is known to have health benefits, and has been used to treat conditions such as seasonal affective disorder (SAD) and non-seasonal depression for some time, no one knows exactly how, or why, it works. The discovery of this new photosensitive system explains a great deal about the ways in which light affects our well-being.

In April 2005, a study published in the American Journal of Psychiatry concluded that bright light therapy is as effective as medication in the treatment of major depressive illnesses and that it has fewer side effects. These and other findings support the age-old belief that we need to be able to see some bright light, or live in sunlit spaces, to stay healthy. Unfortunately, opportunities to benefit from light of sufficient intensity to have a favourable impact on our health can be limited in the modern world. This may explain why depression is becoming so common. According to the World Health Organisation, depressive disorders are the fourth leading cause of ill health among adults worldwide, and by the year 2020 severe depression will be second only to cardiovascular disease as the main cause of death and disability. Significantly, recent studies also suggest Florence Nightingale was right about the positive impact of sunlight on the recovery of hospital patients. Research shows that heart attack victims stand a better chance of recovery if they are in sunlit rooms. Depressed psychiatric patients fare better if they get some sun while in hospital, as do premature babies with jaundice. In addition, patients in hospital wards suffer less pain following surgery if they can see the sun.

Photo: Masaaki Toyura / Taxi Japan / Getty Images

Sunlight Deprivation

The sun’s apparent motion through the sky each day regulates many of the body’s hormonal and biochemical processes. Furthermore, as well as being our external timekeeper, the sun is also our natural source of vitamin D. Of course, solar radiation can trigger skin cancer in susceptible individuals but, paradoxically, the rays that cause tanning and burning are the same ones that synthesise vitamin D in the skin. There is little of this in the normal diet – so anyone who stays indoors when the sun is out may have very low levels of it. Vitamin D has long been known to be essential for strong bones and teeth, but recent research shows that it also plays a pivotal role in maintaining a healthy immune system. There is a growing body of evidence that low levels of vitamin D increase susceptibility to some very common and potentially fatal conditions such as heart disease, stroke, depression, obesity, cancer of the breast, colon, prostate and pancreas, multiple sclerosis, diabetes, and tuberculosis. And just at the time that scientists are beginning to work out how vital adequate levels of vitamin D are to our health, others are starting to recognise just how common vitamin D deficiency really is. A number of recent studies have found disturbingly low levels of vitamin D across all age groups in Britain, the USA and elsewhere. The problem is so bad that rickets is making an unwelcome return.

The focus on the harmful effects of the sun’s ultraviolet rays in recent years has rather overshadowed the benefits they can bring and the dangers of not getting enough of them. For much of its history, humanity has revered the sun as a source of light, life and well-being. The ancient Egyptians worshipped the sun’s healing powers and made good use of them, as did the Greeks and Romans. Lack of sunlight has long been associated with weak bones, weak muscles, mood disorders and ill health. The pioneers of Modernism appreciated this, and so did the architects of Imperial Rome more than a thousand years before them. As the old Italian proverb points out:

“Where the sun does not go the doctor does.”

Dr. Richard Hobday is a leading authority on sunlight and health in the built environment. His recent research includes a study of the impact of classroom design on children’s eyesight; and the use of sunlight therapy in hospitals during the 1918 influenza pandemic. Dr Hobday’s book The Healing Sun has been translated into ten languages and he is also the author of The Light Revolution: Health Architecture and the Sun.

This article is featured in D/A magazine #6, for more information visit