Our understanding of the broader term ‘circadian’ has been reinforced by the huge amount of research that’s gone into this subject. It’s impossible to encapsulate it all in a succinct way, so a general overview will have to do. It’s well documented that circadian rhythms govern how our bodies run and that the 24-hour internal clock is linked to physical and psychological responses such as sleep, body temperature, alertness and hunger. When our circadian rhythm gets out of sync, we need external cues to reset it and light is instrumental in this process. A third type of photoreceptor in the eye called the ipRGC (intinsically photosenstive retinal ganglion cells, to give them their more cumbersome name) is key to this. T ese cells are intrinsically photosensitive due to the presence of a light-sensitive protein called melanopsin. T ey diff er from rods and cones in how they process light – they are not linked to the visual system, but rather the pineal gland – and play an essential role in synchronising circadian rhythms to the 24-hour biological clock. T ey sense the presence of light and send signals to the body to cease the production of melatonin. T is reduction results in feelings of wakefulness and alertness. When these same receptors sense a reduction in light at the end
‘If we don’t start to look at circadian systems in a more holistic way, the eff ect will only ever be emotional stimuli, not the biological response that we’re looking for’
of the day, signals are sent to the body to increase the production of melatonin. T is triggers the start of the sleep cycle. T anks to recent research, we are aware that this photoreceptor is sensitive to short-wavelength (blue) light. Its discovery has profoundly changed how we design with light.
When we start to talk about how artifi cial light can be
used to infl uence circadian rhythms, things are a bit more ambiguous. Lighting designers understand the need to prioritise quality illumination and consider the spectrum of light being used. T e industry talks at length about using cool light in the day to stimulate alertness and warm, low- intensity illumination in the evening to aid rest. It sounds simple, but the truth is that claims are frequently made about circadian lighting that don’t talk about the circadian system at all. Often, the term is nothing more than a buzzword and what we’re referring to is tuneable white light or dim-to-warm schemes where colour temperature and intensity are controlled through scene setting and dimming.
If what we’re alluding to is a dynamic light scheme that is more human focused in its intention, can we genuinely defi ne this as circadian? Personalisation through lighting
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125
