Mood lighting is the use of specific colors or brightness in ambient illumination with the intention of promoting a specific, temporary state of mind or feeling. While not specific to indoor settings, it is most commonly used in indoor environments.[ citation needed ]
Indoor lighting can have a variety of effects on human subjects living or working within an artificial indoor environment. A study with ninety-six subjects, ages ranging from 18 to 55, were examined on how a variety of lighting could impact their mood and cognition. Subjects showed higher problem-solving abilities for females in a warm vs. cool white light source. The opposite result was shown for the male subjects. [1] Field studies have also shown that in office settings, blue-enriched lighting over the course of several weeks can lead to improved alertness, performance, and sleep quality in comparison to lighting with a lower color temperature. [2]
A 2022 psychology study in China found that artificial lighting changes a person's perception of visual objects. Between the participants of the experiment, red and blue light reduced feelings of calmness and stability and increased feelings of irritation and nervousness, while green light reduces the feeling of pleasure and yellow light reduces irritated feelings. [3] Another study states that "increasing evidence from both human and animal studies imply that a specialized class of retinal ganglion cells, intrinsically photosensitive retinal ganglion cells (ipRGCs), plays an important role in the light-regulated effects on mood and behavioral state." [4] A study also found that among people working indoors, "it became evident that the light and colour of the workplace itself also had an influence on the mood of persons working there. The workers' mood was at its lowest when the lighting was experienced as much too dark. The mood then improved and reached its highest level when the lighting was experienced as just right, but when it became too bright the mood declined again." [5]
Deliberate manipulation of ambient lighting is common in indoor or public places where a specific action is intended to be promoted. A common example is the use of ambient lighting in long-haul flights. In 2017, Qantas started Project Sunrise, a series of non-stop, ultra-long-haul flights from Australia’s east coast to London and New York that would include in-plane features aimed at minimizing jetlag and improving customer wellbeing. After a series of research flights, Qantas and the University of Sydney attempted to research the optimal spectral irradiance of light in order to promote circadian adaption, sleep, and wake. The trial produced a series of 12 unique lighting scenes that would be used for project Sunrise flights with the 3 main ones being: Awake, blue lighting to promote awakeness among passengers; Sunset - an immersive transition from daytime mode into dark that gradually imitates the colors of a natural sunset into a night sky including moonlight and a snow effect; and Sunrise - a gradual transition from night to day. [6] The lights were implemented, tested, and "adjusted for eye comfort and appearance" all with the intention of helping passengers adjust to their destination's time zone before their arrival, thus reducing or eliminating jet-lag. Australian Industrial designer David Coan stated that "aircraft lighting doesn’t cross the mind of most travelers but the external light cycle of night and day has more impact on our circadian rhythm and the impact of jetlag than any other factor." [7] [8] Besides passenger wellbeing, the experiment also recorded crew and pilot energy and alertness levels in response to the changes in the ambient lighting. [9] An article by Collins Aerospace states that "light is a key influence in the body’s regulation of the hormone melatonin, the release of which is directly correlated to the time of day and associated light exposure. Melatonin release increases during evening hours to promote sleep and decreases during daylight to encourage alertness – something that is lost when rapidly crossing multiple time zones in a jet." Electrical engineer Eric Johannessen also stated, “a specific blue wavelength that helps to keep us alert during the daytime is removed from the color mix during boarding. This simulates the low levels of light in the evening, allowing passengers to relax and fall asleep faster, even with all the lights on. This system then seamlessly adds the same blue wavelength light back to the color mixture prior to landing, ensuring passengers wake and arrive more rested and alert.” [10] Today, most flights utilize various lighting scenes during food and drink service and rest periods.
Another common use of ambient lighting is in restaurants. For instance, fine dining restaurants and bars frequently use dim lighting, meanwhile brothels and strip clubs frequently use dim, red lighting, such as red-light districts.[ citation needed ] An article by the New York Times states that dim, red light offers a unique juxtaposition with the normalcy and brightness of outside ambience, thus it "embrace[s...] darkroom-core as a way to signal a transition to a nocturnal atmosphere." A customer at one red-light darkroom bar stated, "Red is easy on the eyes...It's fiery. It illuminates, but doesn't overwhelm." [11] Even if the specific color of lighting may not have biologically-wired effects, some specific colors in the present have gradually become associated with specific emotions, a phenomenon known as color symbolism. This includes red, which has become a symbol of various intense emotions, such as passion, anger, and danger, yet warmth at the same time. [12] Other considerations on the impacts of ambient-lighting on mood include how dark lighting could increase anonymity, thus temporarily reducing social anxiety, promoting social interaction, risk-taking, and creativity. A psychological meta-analysis titled "Freedom from constraints: Darkness and dim illumination promote creativity" found that over six studies, darkness and dim illumination improved creative performance. Additionally, the studies demonstrated that darkness elicits a feeling of being free from constraints and triggers a risky, explorative processing style. The meta-analysis stated:
"In the dark or dim illumination, individuals experience less social control and need for compliance to social norms because their behavior is hidden in the dark... [D]arkness induces a sense of being anonymous and unobservable...Overall, dim light apparently creates a cozy atmosphere and induces a feeling of being free from social constraints...Second,...dark and dim lighting conditions also increase risky and disinhibited behavior in the form of prosocial and antisocial deviance from norms. Compared to a well lit room, participants in a dim room were more likely to cheat for their own benefit...However, in dim rooms, participants were also more likely to hug unknown people and disclose private information to others...All these behaviors can be seen as risky because people risk being caught committing negative transgressions and subsequently facing punishment." [13]
Mood lighting can come in several variations ranging from ambient, natural, or artificial lighting. [14] Below are a few examples:
Color temperature is a parameter describing the color of a visible light source by comparing it to the color of light emitted by an idealized opaque, non-reflective body. The temperature of the ideal emitter that matches the color most closely is defined as the color temperature of the original visible light source. The color temperature scale describes only the color of light emitted by a light source, which may actually be at a different temperature.
Light pollution is the presence of any unwanted, inappropriate, or excessive artificial lighting. In a descriptive sense, the term light pollution refers to the effects of any poorly implemented lighting sources, during the day or night. Light pollution can be understood not only as a phenomenon resulting from a specific source or kind of pollution, but also as a contributor to the wider, collective impact of various sources of pollution.
Stage lighting is the craft of lighting as it applies to the production of theater, dance, opera, and other performance arts. Several different types of stage lighting instruments are used in this discipline. In addition to basic lighting, modern stage lighting can also include special effects, such as lasers and fog machines. People who work on stage lighting are commonly referred to as lighting technicians or lighting designers.
The Kruithof curve describes a region of illuminance levels and color temperatures that are often viewed as comfortable or pleasing to an observer. The curve was constructed from psychophysical data collected by Dutch physicist Arie Andries Kruithof, though the original experimental data is not present on the curve itself. Lighting conditions within the bounded region were empirically assessed as being pleasing or natural, whereas conditions outside the region were considered uncomfortable, displeasing or unnatural. The Kruithof curve is a sufficient model for describing sources that are considered natural or closely resemble Planckian black bodies, but its value in describing human preference has been consistently questioned by further studies on interior lighting.
Lighting or illumination is the deliberate use of light to achieve practical or aesthetic effects. Lighting includes the use of both artificial light sources like lamps and light fixtures, as well as natural illumination by capturing daylight. Daylighting is sometimes used as the main source of light during daytime in buildings. This can save energy in place of using artificial lighting, which represents a major component of energy consumption in buildings. Proper lighting can enhance task performance, improve the appearance of an area, or have positive psychological effects on occupants.
Shading refers to the depiction of depth perception in 3D models or illustrations by varying the level of darkness. Shading tries to approximate local behavior of light on the object's surface and is not to be confused with techniques of adding shadows, such as shadow mapping or shadow volumes, which fall under global behavior of light.
A darkroom is used to process photographic film, make prints and carry out other associated tasks. It is a room that can be made completely dark to allow the processing of light-sensitive photographic materials, including film and photographic paper. Various equipment is used in the darkroom, including an enlarger, baths containing chemicals, and running water.
The dark-sky movement is a campaign to reduce light pollution. The advantages of reducing light pollution include an increased number of stars visible at night, reducing the effects of electric lighting on the environment, improving the well-being, health and safety of people and wildlife, and cutting down on energy usage. Earth Hour and National Dark-Sky Week are two examples of such efforts.
Architectural lighting design is a field of work or study that is concerned with the design of lighting systems within the built environment, both interior and exterior. It can include manipulation and design of both daylight and electric light or both, to serve human needs.
International Dark Sky Week is held during the week of the new moon in April, when people worldwide may turn off their lights to observe the beauty of the night sky without light pollution. This event was founded in 2003 by high school student Jennifer Barlow of Midlothian, Virginia. It has been endorsed by the International Dark-Sky Association, the American Astronomical Society, the Astronomical League, and Sky & Telescope.
Computer graphics lighting is the collection of techniques used to simulate light in computer graphics scenes. While lighting techniques offer flexibility in the level of detail and functionality available, they also operate at different levels of computational demand and complexity. Graphics artists can choose from a variety of light sources, models, shading techniques, and effects to suit the needs of each application.
Underwater vision is the ability to see objects underwater, and this is significantly affected by several factors. Underwater, objects are less visible because of lower levels of natural illumination caused by rapid attenuation of light with distance passed through the water. They are also blurred by scattering of light between the object and the viewer, also resulting in lower contrast. These effects vary with wavelength of the light, and color and turbidity of the water. The vertebrate eye is usually either optimised for underwater vision or air vision, as is the case in the human eye. The visual acuity of the air-optimised eye is severely adversely affected by the difference in refractive index between air and water when immersed in direct contact. Provision of an airspace between the cornea and the water can compensate, but has the side effect of scale and distance distortion. The diver learns to compensate for these distortions. Artificial illumination is effective to improve illumination at short range.
An LED lamp or LED light is an electric light that produces light using light-emitting diodes (LEDs). LED lamps are significantly more energy-efficient than equivalent incandescent lamps and fluorescent lamps. The most efficient commercially available LED lamps have efficiencies exceeding 200 lumens per watt (lm/W) and convert more than half the input power into light. Commercial LED lamps have a lifespan several times longer than both incandescent and fluorescent lamps.
Light effects on circadian rhythm are the response of circadian rhythms to light.
Contrast, in physics and digital imaging, is a quantifiable property used to describe the difference in appearance between elements within a visual field. It is closely linked with the perceived brightness of objects and is typically defined by specific formulas that involve the luminances of the stimuli. For example, contrast can be quantified as ΔL/L near the luminance threshold, known as Weber contrast, or as LH/LL at much higher luminances. Further, contrast can result from differences in chromaticity, which are specified by colorimetric characteristics such as the color difference ΔE in the CIE 1976 UCS.
Light in school buildings traditionally is from a combination of daylight and electric light to illuminate learning spaces, hallways, cafeterias, offices and other interior areas. Light fixtures currently in use usually provide students and teachers with satisfactory visual performance, i.e., the ability to read a book, have lunch, or play basketball in a gymnasium. However, classroom lighting may also affect students' circadian systems, which may in turn affect test scores, attendance and behavior.
Color psychology is the study of colors and hues as a determinant of human behavior. Color influences perceptions that are not obvious, such as the taste of food. Colors have qualities that may cause certain emotions in people. How color influences individuals may differ depending on age, gender, and culture. Although color associations may vary contextually from culture to culture, one author asserts that color preference may be relatively uniform across gender and race.
Designing lighting for the elderly requires special consideration and care from architects and lighting designers. As people age, they experience neurodegeneration in the retina and in the suprachiasmatic nucleus (SCN). Less light reaches the back of the eyes because the pupils decrease in size as one ages, the lens inside one's eye becomes thicker, and the lens scatters more light, causing objects and colors to appear less vivid. These symptoms are particularly common with persons having alzheimer's disease. Older people also have reduced levels of retinal illuminance, such as having smaller pupils and less transparent crystalline lenses. Furthermore, as an individual ages, they begins to lose retinal neurons, which not only compromises the ability to see but also to register a robust daily pattern of light-dark that is needed to maintain biological rhythms. The 24-hour light-dark cycle is the most important external stimulus for regulating the timing of the circadian cycle.
North light is sunlight coming through a north-facing window. Because it does not come directly from the sun, it remains at a consistent angle and colour throughout the day and does not create sharp shadows. It is also cooler than direct sunlight due to the way the Earth's atmosphere scatters light via Rayleigh scattering.
f.lux is a cross-platform computer program that adjusts a display's color temperature according to location and time of day, offering functional respite for the eyes. The program is designed to reduce eye strain during night-time use, helping to reduce disruption of sleep patterns.