Following the introduction of artificial light, sunlight became less and less important as a determining factor for waking and sleeping hours.
People in highly developed countries spend far more than half of their lives inside buildings and therefore receive very little sunlight. At the same time they are exposed to a lot of artificial light in the evening and night hours.
This imbalance has a negative influence on the day-night rhythm to which the body's internal clock has always adjusted.
In addition to the eye’s rod cells (for dim light vision) and cone cells (for colour vision), the retina also contains the light-sensitive ganglion cells. They serve the perception of the ambient brightness and play a significant role in controlling the circadian rhythm. The sensitivity of the ganglion cells peaks in the short-wavelength (blue) range between 440 and 480 nm.
The constant exposure of the human eye for a period of 12 to 48 hours to short-wave light of low intensity, such as that emitted by a computer screen, leads to the increased formation of oxygen radicals and, consequently, to damage to the sensory cells. In the long run it results in a loss of visual acuity.
If the eye is intensively dazzled by high levels of illuminance and short-wave radiation, e.g. from the sun or a projector, permanent damage to the retina can occur within a few minutes.
The circadian rhythm and thus the functions of the body are controlled by melatonin. The pineal gland releases the hormone in the hours of darkness in the evening and at night.
Daylight inhibits melatonin synthesis just as nocturnal artificial light in the short wavelength range below 480 nm can suppress the release of melatonin for more than one and a half hours. Even very low levels of luminous intensity are sufficient to lower the melatonin level in the blood. This shifts the day further into the night and shortens the period of sleep accordingly.
Melatonin is important for a balanced immune system and healthy sleep and is also thought to have a cancer-inhibiting effect.
The short-wave radiation from the displays of smartphones, tablets and e-readers and also from computer screens suppresses the release of the sleep hormone melatonin and thus also the ability to sleep. This can be remedied with the help of the software f.lux(r) https://justgetflux.com.
Is darkness a human right like quiet?
In the absence of appropriate light control, lighting systems often illuminate not only the intended areas but also the homes of local residents. Street lighting, building lighting, illuminated sports facilities and neon signs should not annoy, distract or dazzle anyone.
The shielded street (left) only radiates light into half of the lower room. Importance must be attached to a warm white or amber light colour, appropriate illuminance, night-time dimming and parallel installation of the light-emitting surface.
Mushroom-type und spherical luminaires (right) and luminaries with bulbous diffusers radiate the light in all directions and can illuminate people’s homes and cause serious health problems. The light emitted upwards or sideways is an energy- and cost-intensive power loss.
In 2012, the “Light immissions - measurement and assessment” standard came into force in Austria. It defines limit values and shows ways of producing suitable light that has no negative effects on the human habitat and the environment. It is the country's most important standard for the prevention of light pollution.
Immissions from lighting equipment as part of the road traffic infrastructure are not specifically covered, but general requirements for street lighting are listed in the Annex.
If you have problems with public lighting, it is best to first talk to the people in local government or the city council.
In the case of a problem with a commercial lighting installation, talk to the company concerned. If you rent or own an apartment, you can contact the property management, who in turn will contact the company operating the installation.
The problem may be easy to solve, for example by shielding the luminaire in the direction of the residential building or through night-time set back or switch off.
Commercial lighting is regulated under Austrian law by the 1994 Trade Regulations Act (GewO). According to Article 74 GewO 1994, business facilities may not cause a nuisance to neighbours. The relevant authority can be contacted to limit the light nuisance to a reasonable level or to have the lighting installation removed. That requires photometric measurements to be made by an expert and a negative assessment from a medical officer.
If the persons responsible are not willing to talk, a civil lawsuit can be brought in the case of problems caused by street lighting or the illumination of public buildings, churches or sports facilities, although such recourse to the courts can be costly. Another option would be to contact the regional ombudsman or a newspaper ombudsman. This could possibly lead to positive discussions with the operator of the problematical outdoor lighting installation.
In order to ensure that people exposed to artificial light can get enough sleep, the goal should be to ensure that lighting with blue light components (below 480 nm) is switched off by 8 p.m.
In the case of a noise nuisance, the situation is assessed with the window tilted, as a certain amount of fresh air must be guaranteed in the interior. A similar rule should apply to window blinds in the case of a light nuisance, as people cannot be expected to keep them closed.
The human eye involuntarily focuses on the strongest light source and adapts to it. The time available for navigation and hazard detection is reduced. The eyes are strained and fatigue sets in.
Advertising installations such as LED screens, lighting effects with such equipment as skybeamers, flashing warning lights, street lights and oncoming headlights can all irritate and distract the driver, and this can have serious consequences.
More light does not always mean better vision. Intelligent lighting design with glare-free, spatial orientation lighting of the required intensity can increase the level of road safety.
Strong contrasts between light and dark and high levels of luminance cause glare.
The human eye has an excellent ability to adapt to different levels of brightness. Adaptation from dark to light is a fast process, but full adaptation from light to dark takes up to 30 minutes. In the case of a sudden change from light to dark, regular visual perception is not available in the first few seconds. One is virtually blind.
Among other things, the Highway Rules and Regulations (RVS – Richtlinien und Vorschriften für das Straßenwesen) define limit values and specify criteria to ensure that road users experience no significant problems deriving from the traffic infrastructure. RVS 05.06.12 and RVS 05.06.11 define maximum luminance levels (candela (cd)/m2) for non-traffic visual information carriers such as advertising installations in roadside locations.
The 1960 Road Traffic Act (StVO) also includes provisions relating to potential distractions and glare for road users. According to Article 35 StVO 1960 (Avoidance of interference with traffic), the safety of road traffic must not be impaired by any objects. The competent authority may accordingly require the operator of lighting installations which represent a traffic hazard to modify or remove them. According to Article 84 StVO 1960 (Advertising and announcements external to the highway) advertisements and announcements are prohibited outside the built-up area within 100 metres of the highway.
More artificial light outdoors does not mean greater security against violence, burglary or vandalism. There is no conclusive scientific evidence to prove a connection between lighting and the crime rate.
In Bristol (UK), Rheine (Germany) and Liechtenstein, the crime rate did not increase following the decision to switch off the street lighting at night.
The responsible use of artificial light does, however, help to increase people's sense of well-being and subjective feeling of security.
If you want to protect your house from burglary, outside lighting - often also marketed as “security lighting” - is not the answer. If no one is at home, it is better to use a timer combined with economical lighting inside the house. This suggests to potential burglars that someone is at home.
