<str<strong>on</strong>g>licht</str<strong>on</strong>g>.<str<strong>on</strong>g>wissen</str<strong>on</strong>g> <str<strong>on</strong>g>19</str<strong>on</strong>g> <str<strong>on</strong>g>Impact</str<strong>on</strong>g> <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>Light</str<strong>on</strong>g> <strong>on</strong> <strong>Human</strong> Beings <str<strong>on</strong>g>19</str<strong>on</strong>g> 20 21 22 18
Melanopic effects <str<strong>on</strong>g>of</str<strong>on</strong>g> light Outdoors, at home or at work – light is essential for human life. But there is not always enough daylight available. Melanopically effective lighting helps synchr<strong>on</strong>ise our bodily processes with the envir<strong>on</strong>ment. In a developed industrial society, people spend most <str<strong>on</strong>g>of</str<strong>on</strong>g> their time indoors with artificial lighting, living a lifestyle that is increasingly divorced from natural rhythms. Many work shifts or work in windowless buildings. So, like darkness at night, brightness and dynamism <str<strong>on</strong>g>of</str<strong>on</strong>g> daylight figure less and less in the pattern <str<strong>on</strong>g>of</str<strong>on</strong>g> modern daily life. But while outdoor illuminance reaches thousands <str<strong>on</strong>g>of</str<strong>on</strong>g> lux even <strong>on</strong> a cloudy day, the level <str<strong>on</strong>g>of</str<strong>on</strong>g> artificial lighting provided at a workplace is significantly lower than natural daylight. That has c<strong>on</strong>sequences. Too little light during the day can disrupt our internal clock or cause sleep and waking phases to be less pr<strong>on</strong>ounced. Both have a negative effect <strong>on</strong> chr<strong>on</strong>obiological rhythms and may cause health problems. Daylight sets the standard Daylight defines the parameters for biologically effective light: illuminance planarity directi<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> light, colour temperature dynamism <str<strong>on</strong>g>of</str<strong>on</strong>g> light over the day and the seas<strong>on</strong>s. The brightness <str<strong>on</strong>g>of</str<strong>on</strong>g> daylight varies c<strong>on</strong>siderably, depending <strong>on</strong> geographical positi<strong>on</strong>, weather, seas<strong>on</strong> and time <str<strong>on</strong>g>of</str<strong>on</strong>g> day. In Central Europe, most interiors could be illuminated with natural light from around 8 a.m. through to 5 p.m. In the majority <str<strong>on</strong>g>of</str<strong>on</strong>g> cases, however, the daylight admitted by windows does not reach deep into the room. <str<strong>on</strong>g>Light</str<strong>on</strong>g>ing for n<strong>on</strong>-visual effects For technical reas<strong>on</strong>s and because <str<strong>on</strong>g>of</str<strong>on</strong>g> the need to save energy, lighting for n<strong>on</strong>-visual effects cannot simulate natural daylight precisely. But it can provide valuable support. Studies show, for example, that 500 to 1,500 lux illuminance can be biologically effective at a workplace. Melanopically effective lighting can either be additi<strong>on</strong>ally activated or automatically regulated to compensate steplessly for changes in daylight incidence. Harnessing daylight enhances the quality <str<strong>on</strong>g>of</str<strong>on</strong>g> light, makes for a greater sense <str<strong>on</strong>g>of</str<strong>on</strong>g> wellbeing and optimises energy input. For light to reach the particularly sensitive photoreceptors in the lower and nasal part <str<strong>on</strong>g>of</str<strong>on</strong>g> the retina, it needs – like daylight – to come from a planar light source and enter the eye from above. Colour temperature also plays a crucial role: during the day, it should be close to that <str<strong>on</strong>g>of</str<strong>on</strong>g> natural light with a high blue c<strong>on</strong>tent. Another key c<strong>on</strong>siderati<strong>on</strong> in designing artificial lighting for n<strong>on</strong>-visual effects is the need to deliver the right light at the right time. The greatest melanopic effect is achieved after a period <str<strong>on</strong>g>of</str<strong>on</strong>g> darkness, especially in the morning. Apart from supporting l<strong>on</strong>g-term diurnal synchr<strong>on</strong>isati<strong>on</strong>, melanopically effective light can also be used to activate. In this case, for example, illuminance and colour temperature are briefly raised at mid-day or early in the afterno<strong>on</strong>. In the evening, when activati<strong>on</strong> is undesirable, warm light colours and lowered illuminance prepare the body for sleep. Circadian lighting MAX [<str<strong>on</strong>g>19</str<strong>on</strong>g>] <str<strong>on</strong>g>Light</str<strong>on</strong>g> energises and influences our mood. [20 – 22] Like daylight, melanopically effec - tive lighting changes over the course <str<strong>on</strong>g>of</str<strong>on</strong>g> the day: from invigorating cool white light colours and high illuminance levels in the morning, the light undergoes a dynamic transformati<strong>on</strong> that ends in warm light colours and lower brightness levels for the evening. MIN 23 6 a.m. no<strong>on</strong> 6 p.m. midnight 6 a.m. daylight-like lighting with high biological effect light with low melanopic effect melat<strong>on</strong>in horm<strong>on</strong>e level © <str<strong>on</strong>g>licht</str<strong>on</strong>g>.de [23] Daylight-like lighting with n<strong>on</strong>-visual effect is advisable <strong>on</strong>ly during the day (blue curve). At night, in the evening and in the early morning hours, light with <strong>on</strong>ly little biological effect is correct. This avoids any disrupti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> biological processes in the body such as the rise in melat<strong>on</strong>in level (orange) in the evening. <str<strong>on</strong>g>19</str<strong>on</strong>g>