Scientific studies have shown that interior electrical lighting systems can be detrimental or beneficial to our biological systems. Detrimental if we are subjected to too much blue light emitted from our digital devices such as televisions, tablets, and phones (including cool white light) or high light levels at night, which we know to reduce or stop the production of melatonin our bodies need for a restorative sleep.
Lighting can also provide healthful benefits if we just follow the sun and the 24-hour clock as our ancestors did centuries ago. Early morning to midday light levels are at their brightest and blue wave lengths are prevalent. As the sun begins to set, light levels gradually diminish, and red wave lengths become dominant. If we were all able to be outside during morning hours and then again in late afternoon, our circadian clocks would already be set—but that is unrealistic for many of us.
It is especially difficult in hospital and long-term care environments. Bed-ridden patients need lighting that stimulates their circadian system and healthcare providers working night shifts need lighting for circadian entrainment. Only very recently has scientific research provided enough information that allows us to design not just for visual acuity but also for biological support.
Today’s tunable white lighting systems were designed to somewhat mimic daylight indoors—sunrise (cool white light) to sunset (warm white light). These systems can be used to provide psychological support by mimicking the solar day, but it takes more than color tuning to provide circadian support. Requirements for circadian response are constantly evolving through scientific research but we already know that specifying color temperature is not sufficient.
Spectral Power Distribution (SPD) or wave length—and not just “color”—needs to be definitive. More importantly, the lighting system must be able to provide the higher light levels during the day—particularly in areas without daylight—and significantly reduced light levels at night. Recent studies suggest that light level or intensity may be more important for circadian support than SPD.
Hospitals are unique in that they serve a very diverse demographic from newborn to elderly, infirm to energetic, cognitive to confused and anxious. Patient stays may vary from a few days to much longer. Some patients may not be ambulatory and are unable to leave the hospital bed. Nursing staff often do rotating shift work bouncing from day to night shifts in the same week. They must be alert and caring for patients that are sleeping at night. Patients need sleep and not to be awakened by staff turning on overhead lighting.
There have been several studies completed in senior living facilities utilizing color-changing systems that are also programmed for high light levels during the day and significantly reduced light levels at night. Results indicated that residents slept better through the night and were more engaged during the day.
Dynamic or cycled lighting systems aren’t needed everywhere but focus should be where there is little to no daylight access and where people spend extended lengths of time. Often hospital lobbies or waiting areas are daylit and/or have easy access to daylight.
People move in and through these areas and often don’t spend more than a few hours. These spaces would still benefit from the use of dimming controls to reduce light levels at night, save energy, and extend the life of the lighting system.
Here are some ways in which we are guiding our clients as to the where, when, and how to best implement tunable or dynamic lighting systems in healthcare facilities.
NICU, PACU, and CCU: Cycled lighting is critical
The neonatal intensive care unit (NICU) was one of the first areas to use color-changing light to set the circadian clock in premature newborns to get them on the 24-hour clock as soon as possible. Color tunable white light allows for improved light quality over previous fluorescent systems and full-range dimming allows for overall reduced light levels as well as minimal light levels at night.
More so than other areas, great care should be taken to avoid all potential sources of glare to protect sensitive infant eyes. Indirect lighting systems conceal light sources from direct view, minimize potential for glare, and provide diffuse and shadow-less illumination.
All procedure lighting should be controlled separately from room lighting. NICU is a 24-hour operation with healthcare professionals and family members caring for infants day and night. NICU rooms don’t always have windows or access to daylight, so it’s important that the lighting system support all user groups for visual, biological, and even psychological support. Studies indicate that newborns exposed to cycled lighting systems spent more time sleeping, had greater weight gain, spent fewer days on a ventilator, and displayed enhanced motor control both while in NICU and when released. [The NICU Lighted Environment, Mark S Rea, PhD and Mariana G. Figueiro, PhD].
While post-acute care units (PACU) are more transitory, recovery times in some cases can still be significant periods of time. Returning patients to a circadian pattern following surgery and prior to relocation to patient rooms (or hospital release) sets the body systems in motion for correct time of day.
At Shriners Hospital a daylit recovery room provides bright light levels during the day and low light levels at night when electric light sources are dimmed to low. Photography: Lara Swimmer Photography, Architect: SRG Partnership
Critical care units (CCU) typically keep light levels high for the intense level of monitoring necessary in these rooms. However, providing a dynamic lighting system that increases and decreases light according to the time of day has proven to benefit patients and healthcare workers alike. Even with eyes closed, patients can still synchronize with light/dark patterns. In addition to light penetrating the eye, the skin also absorbs light.
Reducing light at night helps to stimulate melatonin for a more restful and restorative sleep, and could, in turn, allow for a faster release to standard patent rooms. Similar to NICU, exam lighting should be specific to each patient bed and separate from the general room lighting.
Nurse stations and patient room circulation corridors: The value of red light
Nurse stations are almost always internal to buildings and without daylight contribution, and nurses work both day and night shifts in a week. Worldwide studies indicate that nurses working night shifts are 50% more likely to develop hormonal cancers than those that work day shifts. Light solutions in these areas become even more critical because they need to support the work task as well as circadian needs. We know that we want to avoid bright light and blue light at night because it prevents the onset of melatonin and we know red light allows and potentially stimulates melatonin levels.
The Lighting Research Center (LRC) created a series of tests in 2015 (which continue today) with shift workers and red light at night. The study indicated that red light did not suppress melatonin (or interrupt the circadian cycle). In fact, the test indicated that alertness and performance increased under the red light.
Zoning of lighting controls is critical to turning lights off (or down) while still allowing enough light for circulation and tasks.
Because nurses are often looking at monitors at all times of day, consideration should be given to how to manage blue-emitted light at night. Most computer monitors allow for color adjustment of the screen that can be adjusted manually or automatically with a program called F.lux. Amber filters are also available to apply to screens but it’s important to ensure that they block out the full range of blue wave lengths, including wave lengths below 440nm.
Staff areas: Balancing for little daylight
Because hospitals are 24/7, many employees do shift-work. Staff areas such as offices, labs, pharmacies, and nuclear diagnostic areas where employees spend full days or nights also tend to be far from windows or daylight. Similar to what we might do in any office space, direct/indirect fixtures provide good ambient lighting that illuminates all surfaces. This can often be accomplished with a single fixture which has an integral occupancy sensor and full-range dimming. Control stations can be manual or preset. Preset stations can be programmed for specific (higher) light levels during the day and reduced light levels at night. Task lighting should always be considered for boosting light levels on the task plane rather than using the general room light for higher light levels.
Patient rooms: Is the daylight effective?
Though most patient rooms today are daylit, patient beds aren’t always close to the windows and daylight may not enter the room far enough to create a biological response to trigger circadian responses. The first step in determining daylight effectiveness in the room is to evaluate the amount of light in the room and its average duration.
Thoughtful design supplements with electrical light sources when needed during morning and early afternoon hours and lighting controls can reduce lighting at night. It’s also important to have overrides that allow the room to be dark if the patient wants to sleep even during the day. Photocell activated amber night lights used both outside and inside the patient bathroom provide sufficient path lighting at night without interrupting the circadian cycle.
Research using lighting systems to synchronize the circadian phase with the solar day is ongoing. We know conclusively that all light—daylight and electric light sources—affect our biological systems and well-being. The right light is critically important in hospitals to benefit patients, their families, and healthcare workers alike.
Lauren MacLeod, IALD, MIES, LEED AP, is a senior associate and senior lighting designer in the Stantec Lighting Design team.