The need for natural light, part III

Let’s see, which hospital room would you rather stay in? This one (A)?

Or this one (B)?

Carson Tahoe Regional Medical Center, Carson City, NV
As for me, I’d choose B. There are lots of reasons why I think B is better than the A, but high on the list is that B has lots of windows that not only look out onto a view that even homebuyers would pay good money for, but that let in copious natural light as well. 

And so we come to the Part III of “The need for natural light.” 

The benefits of natural light – at home, at work and school, and in the healthcare setting – have been well documented. People fare better when they have access to natural light. For example, a 1998 study found that sun exposure in the workplace environment increased worker satisfaction and performance, including lowering intention to quit and reducing fatigue (that same study, by Leather et al., found that providing views of nature also increased satisfaction, particularly in high-stress environments). A landmark “Daylighting in Schools” study found that students in classrooms with more natural light scored as much as 25% higher on standardized tests than other students in the same school district (see references below for full citation and to link to the condensed study). 

As for healthcare: Roger Ulrich and colleagues have found exposure to natural light to be an important factor in environments for healing. Exposure to sunlight can reduce depression, alleviate stress, and even reduce pain. In addition to providing essential dosages of Vitamin D, sunlight increases our levels of serotonin, which in turn inhibits pain. In their recent literature review of evidence-based healthcare design, Ulrich et al. cite a study by Walch and colleagues of post-operative spinal surgery patients. Patients with sunnier rooms reported less stress and took 22% less analgesic pain relief medication (see Ulrich et al, 2008, below). 

In her new, excellent book A Visual Reference for Evidence-Based Design, Jain Malkin lists daylight as one of the key ingredients in creating a successful Environment of Care: “There is a major focus on the importance of natural light and views, access to gardens, and clarity of wayfinding.” In Chapter 4, “Incorporating Research into Design Features,” lighting is first on the list: “Lighting–both natural and electric–is the most important component of an interior environment. Adequate exposure to natural light is essential for biological health and entrainment of circadian rhythm. Research indicates that patients in rooms that receive more sunlight are less depressed and have reduced length of stay.” Malkin also mentions benefits to staff members (pp. 63-65; see full citation below). 
So what does all of this have to do with therapeutic landscapes? 

Simple: Windows that let in natural light… 

The waiting room at Santa Fe Cancer Center at St. Vincent Hospital 
looks out onto the healing garden (Santa Fe, New Mexico)

…can also offer views to the outside world (even skylights can sometimes give us views of blue sky and/or clouds). As Ulrich et al. state in their most recent (2008) literature review, “Larger windows in patient rooms not only provide natural light, but they also have the potential benefit of offering views of nature and should be considered in the design process.” 

Healing garden at St. Vincent Hospital, Santa Fe, NM 
(note the mirrored windows – they provide privacy for those inside 
while also reflecting the garden to make it appear larger).

And as we know from Ulrich’s and other studies, window views to something more interesting than a brick wall, or the building’s air conditioning system, elicit better outcomes. And the research also suggests that more naturalistic the setting, the better the outcome (again, see Ulrich et al, 2008, below).

Lobby at Carson Tahoe Regional Medical Center, Carson City, NV

All of this research notwithstanding, there are times when natural light can be too much of or not enough of a good thing.

Too much of a good thing

1. When light = sun = heat. In hot climates, keeping light out is one important way of regulating the temperature. Whether inside the building or out, people seek shade when temperatures rise above the human comfort zone. Though it’s beautiful and exemplary in many ways, I’m actually not sure how I’d feel in the above Carson City lobby on a hot day in August…but maybe they’ve got it all figured out with awnings, blinds, or some other technology (besides just more AC). 

2. When light = glare. For example, as I write this, the sun is starting to stream into my office, which would be lovely if it didn’t glance off of my computer screen. Time to draw the curtain. And glare can truly be a problem, especially for people like the elderly who are glare-sensitive. 

3. This last point isn’t so much to do with light as with privacy. The one drawback of a window, especially on a ground floor looking out onto a garden, is that if users inside can see out, then people outside can usually see in. Designers of hospitals with interior courtyards often grapple with the double challenge of the “fishbowl effect” (feeling like everyone can see you when you’re in the garden) and not wanting to violate the privacy of those indoors. Designers have found all sorts of clever ways to address this issue, including at St. Vincent Hospital, above, where mirrored windows allow users inside to see the garden whilst keeping their privacy intact, and users outside get the sense of an even larger and more verdant garden (yep, the old mirror trick can work in the landscape as well).

Window coverings: That 1998 workplace study I mentioned earlier also suggested providing users with ways to control the amount of light (curtains, etc.). As we also know from research, providing people with choices is another way to reduce stress and bolster a feeling of control over one’s environment. Whether those operable window coverings are used to control light for temperature regulation, glare, privacy, or just personal preference, they should be provided whenever possible.
Not enough of a good thing: Seasonal Affective Disorder and Sundowners Syndrome. Sometimes natural light has to be augmented or adjusted, as in these two examples below.

1. Another issue with natural light is that in the winter, there just isn’t enough of it. We’ve all heard of SAD – Seasonal Affective Disorder, and this is a real thing. Just as plants need grow-lights in the winter because even sitting in a sunny windowsill isn’t enough, some people need additional light, too. Full spectrum light therapy, at doses of 2500 – 10,000 lux, has been found to be as or even more effective than anti-depressants for some SAD sufferers. 

2. For people with Alzheimer’s and other forms of dementia, exposure to light and the color of light should be controlled and regulated to avoid mood changes and disruptive behaviors, particularly those brought on by “sundowners syndrome.” In two studies by Melinda La Garce, the effects of “Sundowner’s Syndrome” and other light-related problems were reduced by adding “full spectrum lighting to simulate daylight, shading devices to reduce sun angle change and shadows, and light monitors to keep the light intensity the same throughout the day and evening.” In the 2004 study, La Garce noted that the sun’s altitude, which changes over the course of the year, affects the color, intensity, and angle of daylight. She also found that the color of light seemed to play a stronger role than shadows and light intensity. 

As I’ve mentioned in the past (see, for example, “When the Weather Outside is Frightful”),  indoor atria are another great way to provide access to natural light and nature, even on days when going outside is not an option. This image is of the Fourth Floor Atrium at the University of Alberta Hospital in Canada. To see more examples, link to Shane Pliska’s article in Interiorscape Magazine.


Crockett, Jim (2004). “Healthy Daylight and Healthy Darkness: What our Bodies Need.” Consulting-Specifying Engineer. Click HERE to link to the article.

Darling, Tammy (1993). “Seeing the light: why your body needs regular doses of natural light.” American Fitness, Nov-Dec. Click HERE to link to the article.

Gross, Raz, Yehuda Sasson, Moshe Zarhy, and Joseph Zohar (1998). “Healing Environment in Psychiatric Hospital Design.” General Hospital Psychiatry, Vol. 20, No. 2, pp. 108-114. Read the summary by InformeDesign.

Heschong, Lisa and Heschong Mahone Group (1999). “Daylighting in Schools: An Investigation into the Relationships Between Daylighting and Human Performance.” Commissioned by California Pacific Gas and Electric Company. Click HERE to link to the condensed report.

Horowitz, Steven G., M.D. (1998). “Design Trends: Designing for Advanced Therapeutic Outcomes – Acute Care.” Journal of Healthcare Design, Vol. 7. Read the summary by InformeDesign.

La Garce, Melinda. (2004). “Daylight Interventions and Alzheimer’s Behaviors – A Twelve-Month Study.” Journal of Architectural and Planning Research, Volume 23, Issue 3, pp. 257-269. Read the summary by InformeDesign.

La Garce, Melinda. (2002). “Lighting Affects Behavior of Alzheimer’s Patients.” Journal of Interior Design, Volume 28, Issue 2, pp. 15-25. Read the summary by InformeDesign.

Leather, Phil, Mike Pyrgas, Di Beale, and Claire Lawrence (1998). “Windows in the Workplace: Sunlight, View, and Occupational Stress.” Environment and Behavior, Vol. 30, No. 6, pp. 739-762. Read the summary by InformeDesign.

Malkin, Jain (2008). A Visual Reference for Evidence-Based Design. The Center for Health Design

van Bommel, W. J. M. and G. J. van den Beld (2004). “Lighting for Work: A Review of Visual and Biological Effects.” Lighting Research and Technology, Volume 36, No. 4, pp. 255-269. Read the summary by InformeDesign. 

Ulrich, R. S., Craig Zimring, Xuemei Zhu, Jennifer DuBose, and Hyun-Bo Seo, Young-Seon Choi, Xiaobo Quan, and Anjali Joseph. (2008). A Review of the Research Literature on Evidence-Based Healthcare Design. Published in Health Environments Research & Design Journal, Vol. 1, No. 3, Spring, pp. 61-125. Click HERE to read the abstract. 

Ulrich, R. S., C. Zimring, A. Joseph, X. Quan, and R. Choudhary. (2004). The Role of the Physical Environment in the Hospital of the 21st Century: A Once-in-a-Lifetime Opportunity. Concord, CA: Center for Health Design. Read the summary and access the full report at the Center for Health Design.

Walch, J. M., B. S. Rabin, R. Day, J. N. Williams, K. Choi, and J. D. Kang. (2004). “The effect of sunlight on post-operative analgesic medication usage: A prospective study of patients undergoing spinal surgery.” Psychosomatic Medicine, Vol. 67, pp. 156-163.