Michael D White, Previous Senior Lighting Designer at Schuler Shook Theater Planners & Lighting Designers, Minneapolis, USA

https://doi.org/10.36866/pn.113.18

Few events have had greater impact on our species than the development of artificial light. Lifestyles changed dramatically as a result of this invention, including when we sleep, wake, eat, work, and play. Widespread rapid adoption of electric light occurred with the industrial revolution. It allowed the workday to be independent of night time and the seasons. Subsequently, the advent of fluorescent light, along with elevators and air conditioning allowed us to construct buildings that are tall and wide and have little natural light. Nowadays, most people spend around 90% of their time indoors, and the use of light at night has increased as well. The pattern of light and darkness in the modern world is quite different from the light-dark cycle under which life evolved. From the perspective of an evolutionary timescale, these changes have been essentially instantaneous and the effect on health has been profound.

Chronobiology informing design

Scientists have been connecting the dots from circadian circuitry in the eye to the master clock in the brain to rhythmic gene expression in every cell and rhythmic physiological processes such as melatonin secretion and sleep. Moreover, elucidation of the differential impact of light spectra, light intensities and times of exposure, and previous light history has informed design. Knowing how an individual’s light/dark exposure affects health and behaviour has allowed architectural lighting designers to integrate light in architecture for health. An understanding of the cause and effect allows us to develop innovative solutions. At the University of Minnesota Masonic Children’s Hospital in Minneapolis, Minnesota, I was part of a team that implemented a lighting and controls system in a paediatric intensive care unit. The design intent was to use light and darkness to positively affect patient outcomes.

In a hospital room, every item is planned with respect to size, colour, finish, and location (Fig. 1). There are three sources of light – overhead, from the window, and from computer screens. Over the bed is the requisite four-lamp fluorescent light, which produces a field of bright light, needed during examinations and medical procedures. While this satisfies the code requirement, the glare it produces is unacceptable, so the fixture is typically switched off. As the windows are approximately 15 feet (4.57 metres) behind the patient, little natural light reaches the patient’s eyes. At night there is a glow of light from the corridor and computer screens.

The overall result is a kind of 24/7 twilight punctuated by periods of bright light at random times. This is an extreme environment where patients receive no environmental cues to indicate day or night, and worse, they get false cues from the exam light. They have difficulty sleeping and often slip into delirium or depression which negatively affects their health and makes treatment more difficult.

As part of a continuous development programme, the hospital engaged a design team to create an environment that would resolve these issues. Together, we developed a set of objectives to guide the process.

Objective 1: Maximise brain and body rest using maximal darkness exposure

The first design task was to design the darkness. This was the hardest objective to achieve because it is beyond the scope of normal consideration – designing darkness is a novel concept. Nonetheless, we used improved drapery to shield against light spilling from the family area and the corridor. We also eliminated windows that open onto adjoining rooms. Understanding that caregivers must have light to do their work, we developed specific control settings for use at night so that patients are exposed to as little light as possible. With all elements in place, the minimum intensity measurement was 5 lux (a measure of light intensity on a given surface). Whilst good, the ideal would be closed to 1 lux, which is the intensity of a full moon. The overall intent is to provide an extended period of darkness so that melatonin is released into the patient’s bloodstream and vital night-time processes can occur.

Objective 2: Synchronise timing of wake/sleep onset to developmental age using the first two hours and last two hours of light

The fixtures over the bed have colour-tuning capability, meaning that the quantity and spectral output can be controlled. This allowed automatic delivery of a carefully controlled dose of light to the patient between 8 am and 10 am in the morning. The dose was calibrated to deliver enough light at the eye to stimulate our master clock, the suprachiasmatic nucleus, suppressing the production of melatonin, and beginning the cascade of physiological events that normally happen during the day (Lucas et al., 2014).
During the hour prior to bedtime, the quantity of light in the room is slowly reduced and the blue part of the spectrum is removed. The intent is to prepare the patient for sleep by restricting exposure to light. The timing of this change depends on the age of the patient. The young children
go to sleep at 6 pm, while teenagers can stay up until 10 pm.

Objective 3: Liberalise light use during middle of the day, within limits; maximise alerting during engaging activity, minimise light exposure during rest

The system is designed to allow patient control over the lighted environment. Using a touch screen mounted on a boom-arm, the patient can control the system for most of the day. The lighting overhead and on the wall wash can be adjusted for colour and intensity (minimum 10 lux during the daytime). The light can be warm or cool, bright or dim. Programmed sequences are available that suggest rainbows, fireworks, or northern lights. We also developed lighting sequences that play in conjunction with a series of lullabies, composed by music therapists. The light and sound sequences help patients relax and get to sleep.
A controlled study of effect of light and darkness on patients is planned. Initial anecdotal evidence from caregivers is positive, and they are assigning some of the most critical patients to the three rooms with the new system.

References

Lucas RJ, Peirson S, Berson DM, Brown TM, Cooper HM, et al. (2014). Measuring and using light in the melanopsin age. Trends in Neurosciences 37(1), 1–9.
https://doi.org/10.1016/j.tins.2013.10.004