HUMAN RESPONSES TO LIGHT - HEALTHCARE EDITION

HUMAN RESPONSES TO LIGHT – HEALTHCARE EDITION

EPA’s Lighting team have been following current lighting research into the human responses to light and the influence these have on human health, well-being, productivity and emotions. Human beings have evolved to function under daylight, and as we know, this level and colour of light naturally changes throughout the day. These natural changes range from bright white light to softer warm tones at night. Humans have adapted to this circadian cycle over 120,000 years of evolution, however as we are moving to spending most of our time in indoor environments, artificial lighting must cover the role and responsibility of ensuring our bodies natural circadian rhythm is still healthily operating.

Research has shown that carefully designed lighting environments can increase mental well-being, comfort and alertness, but in healthcare environments, can also lead to measurable improvements in patient recovery outcomes. When thoughtful and effective lighting is embraced, one can truly appreciate the perceptual, behavioural and psychological effects of light as a fluid medium, not just a stationary effect.

Lighting is an important factor in healthcare which must create a balance of ambient lighting for the comfort of the patients with functional lighting for the tasks carried out by the staff. Some of the important human health and wellbeing factors that are considered when illuminating healthcare environments are expanded below.

HUMAN CENTRIC LIGHTING 

Humans are the centre and core of all our lighting designs, human centric lighting aims to create a naturally illuminated environment with artificial lighting. Research has indicated that with a significant move to the indoors over the course of human evolution, this has significantly impacted the benefits of natural light on human health and productivity. 

Recent discoveries have uncovered a novel photoreceptor in the eye called the intrinsically photosensitive retinal ganglion cell (ipRGC or ganglion cell for short). This ganglion cell is stimulated by light wavelengths in the blue colour spectrum, it works with our natural body clocks to regular the secretion or suppression of a neurochemical, called melotonin.

Human circadian rhythms, or our natural body clocks, rely heavily on the changing times of day and the subsequent changing colour temperature of the sun between sunrise and sunset to perform basic productivity requirements during our day-to-day activities. The rising of the sun in the morning and the bright cool white light post sunrise, suppresses melatonin and activates our circadian rhythms for an alert and productive day. The dimmer warm white light before the sunset releases melatonin and calms our circadian rhythms and naturally prepares the body for sleep. Sleep is the most important function of our circadian rhythms, ensuring the body regenerates, rests and recovers for the following day. The cost of inadequate sleep is enormous, and can result in chronic fatigue, loss of productivity, loss of motivation, high risk of errors, depression and in severe cases high risk of crime, financial loss, higher risk of car accidents, microsleeps and death.

Artificial lighting research and technologies over recent years have implemented tuneable white lighting which mimics the changing colour temperatures of natural light (daytime – sunset).  Colour range of tuneable white luminaire products should be tailored to suit each space with colour temperatures ranging from 2200K-6500K in some cases dependent on the task and needs of occupants of the space.

MELATONIN RELEASE

Sleep deprivation compromises general health and well-being. It can also alter social behaviour, emotional judgement and regulation. Specific occupational groups such as healthcare workers and those working in safety critical environments may be at increased risk due to abnormal sleep and light exposure patterns with lighting requirements being extremely diverse. Within some of these environments, sleep and recovery are important design elements. Evidence strongly suggests that compromises to sleep can significantly impact the immune system, patient recovery and overall well-being.

Melatonin is a hormone which the body naturally releases into the brain which instructs the body to sleep, the rise of melatonin signals the beginning of the biological night. Lighting designs for healthcare environments must encourage the natural release of melatonin, at the right time, to improve quality of sleep. Lighting is a significant tool in the development of targeted sleep and circadian strategies to maximise alertness, enhance cognitive health, and promote occupational safety and productivity. Negative emotions are most affective when sleep deprived – sleep deprivation reduces trust and increases selfish behaviour during social exchanges. During sleep restriction there is a reduced functional connectivity between the emotion regulation centre and emotion processing centre within the brain, leading to enhanced reactivity to negative stimuli.

MELATONIN SUPRESSION

By implementing the use of bright cool white light, the body naturally supresses the hormone melatonin with a greater physiological response, activating alertness and enhancing mental processing speed and concentration. For healthcare and shift workers, it is imperative that during their working hours they are in an environment which enhances a positive mood, increases working performance, reduces fatigue and delays sleep onset. Recent research completed by Andrew Philips at Monash University has shown that bright cool white light during the day can also enhance the immunological response and reduce organ injury during an infection.

LIGHTING FOR COMFORT 

Patient comfort is the most important factor in any healthcare lighting design. Comfortable glare free lighting creates a calm and relaxed environment for patients. This feeling of comfort has been proven to improve and accelerate patient recovery and patient experience in healthcare facilities.

Glare free lighting limits the direct visibility of light sources, whilst utilising in-direct lighting elements to create soft ambient atmospheres throughout the space. This is achieved through luminaires with a low glare rating.

DISTRACTION THERAPY 

Distraction therapy is a simple yet effective capability of lighting design, distracting the patient from the reality of their current situation or upon lead up to high stress event (such as surgery). Implementing warm colour temperatures, colourful lighting effects and seamless yet decorative lighting elements to draw the attention of the patients and add a distraction to any negative emotions or tasks at hand.

Alongside colour temperatures and colour lighting techniques, lighting projections which create shapes of light and colour aid the effect of distraction therapy and help implement calming effects for patients.

COLOUR RENDERING 

Colour rendering properties of lighting technology has improved exceptionally through lighting research in recent years. A high colour rendering through artificial lighting can more closely replicate natural light and render the colour as seen under natural light conditions. As close an accurate representation to the natural eye as possible. 

CYANOSIS LIGHTING 

Cyanosis is a medical term which refers to the skin turning a bluish/purple colour, indicating signs of many possible serious illnesses. Cyanosis Lighting is required for all patient and examination areas to clearly identify the bluish discolouration in the skin and mucous membranes, which indicates that oxygen levels in the blood are dangerously depleted.

The ability of medical staff to reliably detect the onset of cyanosis by visual observation may be critical to a patient’s well-being. This is achieved through luminaires with high colour rendering of CRI > 90 - 95.