ROOFLIGHTS - Better quality of light: better quality of life.

Aug 11, 2017

Assessing the positive impacts of daylighting 
in buildings on health & wellbeing.

A look at reasearch into daylighting in healthcare buildings published by the BRE and additional information from NARM, the National Association of Rooflight Manufacturers.

Sunlight plays a vital role in human health – and while in recent years there has been publicity about skin conditions which can be caused by over-exposure to damaging UV rays, the World Health Organisation states that in fact a markedly larger global disease burden results from inadequate exposure to daylight.

Exposure to sunlight enhances mood and energy through the release of endorphins (hormones which have a euphoric or even painkilling effect). In fact, daylight is critical to mental wellbeing - as evidenced by the growing understanding of the condition known as SAD - Seasonal Affective Disorder, caused by inadequate exposure to daylight.

Daylight is recognised as contributing to healing processes and fighting infection

Many buildings constructed over the past 70 years which rely heavily on artificial light*, have a negative impact on human health, productivity and wellbeing. In extreme cases the buildings are responsible for debilitating health problems associated with Sick Building Syndrome (SBS).
The issues associated with SBS and/or daylight deprivation, coupled with a renewed interest in the use of daylight in the design of low-energy, sustainable buildings is leading many architects and engineers to consider new ways of exploiting the benefits of daylight without the negative impacts associated with solar over-heating.

However, there are concerns that current health implications associated with excessive solar exposure, could inhibit the re-emergence of a renewed interest in solar architecture. The BRE Group states that: “It is critically important that the positive benefits of daylight do not become confused with the negative impacts associated with excessive solar radiation, not least because modern glazing can reduce the transmission UVs.”

Daylight in healthcare environments

In healthcare environments, the benefits of high levels of daylight are particularly significant. Following are just a few of the remarkable facts revealed by recent research studies, as published by BRE – the Building Research establishment.

Access to daylight enables patients to be discharged from hospital sooner than patients without daylight access

A study published in 2012, found that; ‘A significant relationship appears to exist between indoor daylight environments and a patient’s average length of stay (ALOS) in a hospital. 25% of the comparison sets showed that, in the brighter orientations, as in rooms located in the SE area, the ALOS by patients was shorter than that in the NW area by 16%-41%.

In 2006 a comprehensive review of the impact of light on outcomes in healthcare settings found that;
‘A retrospective study of patients in a cardiac intensive-care unit treated in either sunny rooms or dull rooms found that female patients stayed a shorter time in sunny rooms (2.3 days in sunny rooms, 3.3 days in dull rooms). Mortality in both sexes was consistently higher in dull rooms.

There is a clear link between daylight/sunlight and a reduced requirement for pain relief medication in hospitals

The use of analgesic medication can result in side-effects and for this reason any strategy which reduces the requirement for pain-relief medication is desirable.

A study of patients undergoing spinal surgery, published in 1995, concluded; ‘Patients were assigned postoperatively to rooms on either the bright or dim side of the hospital unit. Those on the bright side received 46% more natural sunlight and required 22% less analgesic medications during their hospitalization. These patients also experienced a 21% reduction in analgesic medication cost compared with patients on the dim side.’

At least 11 strong studies suggest that bright light is effective in reducing depression among patients with bipolar disorder or seasonal affective disorder (SAD)

One of the studies found that bipolar depressed inpatients in east-facing rooms (exposed to bright light in the morning) stayed an average of 3.67 days less in the hospital compared with similar patients who stayed in west-facing rooms.

Exposure to bright morning light has been shown to reduce agitation among elderly patients with dementia

Elderly residents in facilities with low light levels have been shown to display higher agitation levels – and exposure to bright morning light reduces agitation among elderly patients with dementia. When elderly patients with dementia were exposed to 2,500 lux for 2 hours in the morning for two 10-day periods, their agitation reduced. Patients were significantly more agitated on non-treatment days.

Experiments undertaken in the USA and the UK between 1941 and 1944 demonstrated the extraordinary and remarkable effectiveness of daylight in killing bacteria

Even diffuse daylight passing through two layers of glass from a north window was found to be highly effective in killing streptococci bacteria within 13 days, with the same strain surviving in the dark, at room temperature, for 195 days.

The trials also examined the bactericidal effects of artificial light, which was found to have little value as a disinfecting agent.

No significant further work on this issue has been undertaken since the mid-1940’s. This is surprising given the current concerns regarding MRSA and other other highly infectious bacteria prevalent in many hospitals, which are becoming increasingly resistant to treatment with commonly prescribed antibiotics. It is interesting to reflect that if daylight has such a dramatic and potent impact on killing streptococci, it’s surprising that its potential for reducing super-bug infections in hospitals, has not been fully investigated.

Experts have also speculated that sunlight may prevent heart attacks in a similar manner to antidepressants by alleviating depressive symptoms.

The weight of evidence in favour of high levels of daylighting in healthcare buildings is supported by other studies into the health, wellbeing and performance of building occupants carried out in other sectors. In education; leisure; commercial facilities; dwellings… in fact wherever people spend time inside buildings, appropriately designed daylighting should be considered beneficial.


Research referenced by the Building Research Establishment and published on

An Introduction to Daylighting with Rooflights - RIBA approved CPD Seminar by NARM, available on-line at:

* The advent of air conditioning and flourescent lighting in the twentieth century led to a trend for deeper plan buildings, in which natural light cannot reach many internal areas.

Feb 6, 2018

NARM, the National Association of Rooflight Manufacturers, is celebrating its 20th Anniversary in 2018. NARM is an active trade association representing UK rooflight suppliers and associated businesses. The Association is dedicated to the application of best practice in the provision of natural light in built environments.

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