Turning on the light to navigate our surroundings and perform tasks is such an integral part of life that it has become a global reflex. We automatically expect to have some form of illumination in the built environment whether at home, in the office or within public buildings. It is commonplace, it is simple, it is the primary function of a lamp yet beyond driving out the darkness and looking fancy, it exists. Perhaps its clichéd existence accounts for its many facets going unnoticed or being taken for granted, nonetheless it impacts our daily lives and may even have long-term consequences on well-being. Lighting influences our moods, our perception and experience of architecture as well as our health and productivity. For better or worse, we are affected by mere light bulbs. This piece takes a delve into these facets of lighting and highlights its complexity as it pertains to human interaction with the built environment.
For most people, walking into a dim, warmly lit room evokes feelings of intimacy, relaxation and comfort. In fact, while reading this article, you may very well recall the boneless feeling of a long relaxing soak in a bath tub or lounging with a loved one on the living room couch while watching television. Conversely, a cool, brightly lit room keeps us alert and productive and may conjure up images of meetings in a conference hall or visits to the dentist. Seemingly bizarre, the science shows that these reactions and associations are not arbitrary, rather they represent the body’s response to light.
The truth is found in the body’s circadian rhythm. Circadian rhythm is said to align with the sun’s cycle of rising and setting and is intended for healthy functioning during the day as well as rejuvenating sleep at night. This rhythm is mainly mediated by the hormones cortisol (A.K.A stress hormone), and melatonin (A.K.A sleep hormone). Cortisol, which peaks around 8AM, regulates stress and keeps us alert so we can tend to the day’s activities while melatonin begins to kick in around 8PM and encourages rest and sleep. “How exactly does the body know whether it is day or night?” you might ask. The short answer is, the eyes.
Within the highly sophisticated eye is the retina which contains the rods and cones that capture light rays. These cells are called photoreceptor cells and are responsible for vision at low light levels and colour vision respectively. Light rays absorbed by these cells are converted to chemical information that is transmitted by the optic nerve to the brain for processing and interpretation. This is how we see. Additionally, within the retina are intrinsically photosensitive retinal ganglion cells (ipRGCs) which do not contribute to vision, but contain melanopsin. Melanopsin is a light-sensitive protein which when excited by wavelengths and intensity of daylight sends information to parts of the brain that regulate the production of the hormones that maintain biological rhythm.
Thus, eyes are the link between internal regulation and the exterior. Inadequate exposure to daylight, blue-light from mobile devices which may interfere with adequate production of melatonin and disrupt sleep and lighting at intensities, wavelengths and colour temperatures that do not support internal regulation all result in disruption of the clock. Consequences include sleep disorders, reduced productivity and may increased risk for depression and obesity.
Increased exposure to natural light has been shown to improve productivity and improve moods and should be incorporated in design. Furthermore, the use of lighting technology that mimics the progression of daylight in intensity and colour temperature may be employed as well as dimmers and controls that give individuals control over their lighting.
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