Light and Health

Light and Health

Polar Ray Admin

Light, both natural and artificial, impacts human health in many ways, both good and bad. Besides the most obvious ability to enhance or enable the performance of visual tasks, light has an enormous effect on the body’s circadian system. That effect on the circadian system can lead to many potential health problems. Light also has a big impact on mood and perception and plays an important part in critical chemical reactions within the human body.

Studies have indicated that, in regard to accomplishing visual tasks, the performance of the visual task to be accomplished is increased as the light level increases. In further investigation it has been revealed that the nature of the task, in concert with the amount, distribution, and spectrum of the lighting has a direct effect on the level of performance that is attained. Tasks such as reading and writing are able to be performed under artificial light as well as natural light – given that the light is distributed in the correct amount. Until the introduction of the fluorescent light, the spectrum of the lighting was pretty much a given - being about rated at around 2700K. Even that spectrum provides a decent light color for reading and writing, and most folks are fairly comfortable with the spectrum of light produced by incandescent lights because in most residential settings, until recently, incandescent bulbs, or even low color rating CFL bulbs were what was used. The change in the ability to obtain differing spectrums of artificial light has now become even more readily available and practical (vs. fluorescent tubes and CFLs) with the commercial success of LED lighting. While the everyday tasks of reading and writing can be comfortably accomplished under low spectrum lighting, daylight is superior for determining color rendition. However, LED technology is knocking on the door of artificial light being as good as daylight.

Light has a very definite effect on the body’s circadian rhythm which, in short, synchronizes our internal clock to a 24 hour period. Without workday rhythms being guided by our internal rhythms, symptoms such as being tired, distracted, and detached from tasks become quite evident. Because of the way in which the human body is controlled, the normal 24 hour rhythm is being awake during the daylight and sleeping during the dark of night. When these rhythms are changed, results can be dramatic. The exposure of light – both/either natural or artificial – is necessary to many bodily functions including the activation of the gland th at results in the control; of melatonin. Melatonin levels determine a person’s levels of energy and activity, and if light is not adequate during the day (waking period) the melatonin levels are not held in the natural suppression and the high levels of melatonin cause feelings of depression and sleepiness.  

The exposure to light - in particular, daylight - is key to determining the phase of the circadian rhythm of an individual. Although artificial light is capable of mimicking the effects of creating the rhythm, daylight provides a greater level of light that is best matched to the natural circadian rhythms. The control of the circadian rhythm system by both natural and artificial light has proven to impact many health issues in studies of both staff and patients in hospitals. These issues involve cases of depression, sleep disorders, and even patient length of stay when circadian rhythms are disturbed by some event.

There are about a dozen well known studies which suggest that bright light is an effective help in reducing depression, as it is believed that the intensity of the light is effective in suppressing the high levels of melatonin. In one study it was shown that patients in east facing windows, which provide bright morning light, cut their hospital stay by around 3.5 days when compared to patients with similar ailments who were staying in rooms with west facing windows. The evidence, from numerous studies strongly suggests that exposure to bright light in the morning is more effective in reducing the symptoms of depression than the exposure to bright light in the afternoon and evening. One study involving winter depression compared the effects of morning and afternoon/evening light determined that the exposure to morning light was twice as effective as evening light in treating seasonal depression. In fact many studies not only suggest, but prove that exposure to early morning light has very positive effects on improving many physiological and psychological issues that we as humans are susceptible to. So, wake and bask in the brightness of the morning sun and make your life smile.

As always, if you need help with your LED lighting projects, please feel free to call Polar Ray at 303-494-5773 to speak with a lighting consultant. Thank you for perusing the Polar Ray website.