Interior light effects on human mood and social behaviour
Nowadays, the scientists, designers and psychologists are believed that the lights can play the important roles on human mood and people social behaviours. In this way, this research area introduced new concept in industrial, commercial and home designs in few last decades.
Referred to as "the prime animator of space," light is a subject of broad application within the environmental design disciplines .Recently, scholars posit that light is most often applied to an interior design solution as a functional additive rather than considered first as an essential design element along with form, colour, texture, and others. This raises the question of how designers', educators', and students' approaches to designing with light might be redefined to regard light as a significant contributor to spatial compositions.
Well-designed lighting is one of the most important design elements that will support an individual's ability to perform normal daily activities and decrease the level of disability associated with these impairments. Daylight contains the spectrum to which the circadian clock is most sensitive and provides higher light levels during the day. Easily accessible outdoor gardens encourage individuals outside, providing the necessary regular exposure to direct bright light that sunlight provides. The combination of good interior lighting and regular daylight exposure contributes to regaining and maintaining an active and fulfilling lifestyle – greatly improving quality of life .
More recently, researchers have realized that the components of service quality are interrelated and the issue must be approached from a broader perspective . A comprehensive understanding requires examination of all the factors that influence the perception of service quality and clarification of the role that the interior environment plays in this perception. The interior environment is comprised of the physical and ambient elements within a service establishment’s control. Although the design of such elements falls squarely within the expertise of the profession of interior design, service quality research has been conducted within the business community without reference to design knowledge. Charlotte R Bell  firmly established the business basis for embracing interior design in the place of service and to add to the interior design body of knowledge.
Generally, the environmental issues have two aspects. First, the effects of human activity on ecological stability and second the effects of the environment on human health and well-being. A research group  believes that lighting cans highly affecting on health, performance, mood and social behaviours. They used 32 different lighting items to create a questionnaire for analysis few important elements and show the affects of light in human behaviours. This elements are includes of brightness, day lighting, social setting, etc. The designed questionnaire can be used to explore responses to interior lighting and to discover what beliefs are held by end users. This information will assist in allaying unwarranted fears and concern about new lighting technologies in close future.
Yoshika miwa et al  examined the effects on interior design on human communication and impressions by reconstructing the counselling room decoration and changing the room colours. In this case, they design four different room decoration and they combine this decorations with two different light types. They assigned random undergraduate students as a client in each designed room. Also, they assigned one individual interviewer to each client as a consular. In continue, the clients filled the given questionnaire in different mental mode based on dim or bright colours. The result shows that the combination of different decoration with dim colour is more pleasure and relaxes feeling for clients. However, the authors found no predominant pattern of the decorations. Thus, the pleasant and relaxed feelings related to dim lighting may well enhance the perceived attractiveness of a counsellor and self-disclosure from clients. The results imply that interior design could influence communication and other relationships in counselling rooms.
Somehow, a large group of the researchers are believed that the lighting conditions can effects on personal space requirements. Leslie Adams and David Zuckerman  demonstrated that a reduction in lighting and a decrease in room size have similar effects on interpersonal space requirements. They selected 28 female students in their experimental and these students were measured under both bright and dark conditions by using stop- distance technique. Interpersonal closeness was found to cause significantly less discomfort under high illumination than it did in relative darkness.
Moreover, they found that the angle of approach is important in the human pleasures. Finally, they shown in their report that distance requirements increased as the direction of the approach progressed from front to rear. The spectrums of different colours can highly affecting on human mood and cognitive performance. In this way, the study of affecting indoor colours on human mood is one of the significant scopes to examine the social behaviour and human reactions. K. Yildirim et al  use this concept in their studies and they investigated that the impact of the indoor colours, gender and age can be affecting elements on human social behaviour. They introduced a theory that indoor colours for decoration in stores are an effective source that may convey emotional meanings differentiated by gender, age, or both. In order to study this, a two-stage work was carried out in a café/restaurant, in which interior yellow walls were changed to violet. In both stages, furniture and decorations remained the same. Each appearance (yellow and violet) was tested by using visual attributes through the use of bipolar scales. Results from approximately 250 participants for each stage showed that violet interiors were more positively perceived when compared to yellow. Compared to females, male users evaluated the space more positively. In addition, young customers had a more positive tendency than older customers towards the perception of atmospheric attributes, including colour of store interiors.
Moreover, R. Kuller et al  represents in their research work that whether indoor lighting and colour would have directly have deal with systematic impact on the people working indoors. Their study was carried out in real work environments at different seasons and in countries with different latitudes. The present study was carried out in real work environments at different seasons and in countries with different latitudes. A total of 988 persons completed all parts of the study. In the countries situated far north of the equator there was a significant variation in psychological mood over the year that did not occur in the countries closer to the equator. When all four countries were considered together, 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. On the other hand, the illuminance as measured in objective terms, showed no significant impact on mood at any time of the year. The relationship between mood and the distance to the nearest window was bimodal. The results also indicate that the use of good colour design might contribute to a more positive mood. It is suggested that in future research light and colour should be studied as parts of the more complex system making up a healthy building.
Nowadays, lighting and using different colours in residential and commercial buildings can play an important role in the entertainments, business and many other related fields. In matter of fact, these two elements have highly effect on customer’s emotional states, preferences and behavioural intentions . For example, designing hotels is one of the mentioned subcategories which can present the interior light effects on human mood and social behaviours. The study of lighting in hotel design shows that there is a positive relationship between pleasure and preference. Joo youl Pae conducted few fundamental experimental results to compare American preferred guestroom and Korean preference based on lighting and colours design. He found that “American subjects preferred the hotel guestroom with low intensity and warm colour lighting the most while Korean group rated the hotel guestroom with high intensity and warm colour lighting as the most preferable one”. He formed a sample consisted of 175 adults, 87 American and 88 Korean. Moreover, he found in his study which “American participants perceived dim lighting as more arousing than bright lighting while Korean participants evaluated bright lighting as more arousing than dim lighting”. At the end he represented in his experimental results that “ American participants responded under the dim lighting condition that they would recommend the guestroom to their friends, while Korean participants responded under the bright lighting condition that they would stay longer in that guestroom”.
Anne Baumstarck  studied the effects of interior light effects on human mood by investigating on dressing rooms. Dressing rooms are keys to the retail experience and often represent that final moment where the consumer decides whether or not to make a clothing purchase. Therefore retailers need to understand what affects this decision point in order to increase sales. The effects of lighting have been investigated in his research as one of the most important elements in dressing rooms. In this way he examined how the physical environment affects consumers along any key dimensions in the dressing room. The physical environment encompasses both architectural elements such as physical layout, furniture, and equipment and visual sensory elements such as colour, texture, and lighting. These two aspects, in conjunction with ambient factors, create the interior environment .
A researcher  has been studied the light distribution for offices by using computer simulation using the program Rayfront/ Radiance and Daysim. The effect of a few façade alternatives has been compared regarding daylight availability and visual comfort. The study focussed on single-cell offices, but open-plan space has also been studied. The conclusion is that very large windows do not mean that the light is automatically better. It can be difficult to achieve a glare free environment without additional measures, for example by adding interior curtains or blinds. Today’s computer based work which includes looking at vertical self-luminous surfaces also increases the risk of glare compared to looking down on a piece of paper. The line of sight is raised and the central field of view will most likely include the window, especially in open plan spaces. The larger the window area, the greater is the chance that a window might create glare. In order to further reduce glare risks, the computer screens could be moved further away from the window, and turned away from the window, to a perpendicular position. I
ogr Knez  conducted few important tests in his research to study the impact of indoor lighting, gender, and age on mood and cognitive performance. It was hypothesized that indoor lighting is an affective source that may convey emotional meanings differ entailed by gender, age, or both. A two-way interaction between type of lamp and age on negative mood showed that younger adults (about 23 years old) best preserved a negative mood in the “warm” (more reddish) white lighting while working with a battery of cognitive tasks for 90 minutes; for the older adults (about 65 years old), “cool” (more bluish) white lighting accounted for the identical effect. The younger females were shown to preserve the positive mood as well as the negative mood better than the younger males, and a main effect of age in all cognitive tasks revealed the superiority of younger to older adults in cognitive performance.
Three studies examined  the effects of key aspects of indoor lighting (illuminance, spectral distribution) on the performance of tasks that did not primarily involve visual processing. It was hypothesized that lighting conditions which generated positive affect among subjects would influence behavior and cognition in ways consistent with the findings of previous research on the influence of such affect. Results of all three studies offered partial support for this hypothesis. In Study 1, male and female subjects exposed to relatively low levels of illuminance (150 lux) assigned higher performance appraisals to a fictitious employee and included a broader range of words in specific word categories than subjects exposed to relatively high levels of illuminance (1500 lux). In Study 2, subjects exposed to warm white light reported stronger preferences for resolving interpersonal conflicts through collaboration and weaker preferences for resolving conflicts through avoidance than subjects exposed to cool-white light. Additionally, illuminance and spectral distribution (colour) interacted to influence subjects' self-set goals on a clerical coding task. In Study 3, receipt of a small, unexpected gift and exposure to warm-white light both increased the amount of time subjects were willing to donate as unpaid volunteers. In addition, in the absence of a gift, subjects volunteered more time under low than under high illuminance.
A.WALL and L. BERRY  are discussed in their paper which there is different clues to judge the restaurant experience; : functional—the technical quality of the food and service; mechanic—the ambience and other design and technical elements; and humanic —the performance, behaviour, and appearance of the employees. One of these judge elements is lighting which it is related to human mood and customers behaviours. In this part they found that in the restaurant the soft lighting, snowy white linen tablecloths, and crystal chandeliers of an upscale restaurant communicate to customers the type of food and level of service that make up a fine-dining experience. Moreover, they investigated in their research which atmospherics has focused on the effects on customers of specific ambient factors, which are background conditions such as lighting or music that affect the senses, often subconsciously.
Hilary Dalke et al  studied on colour and lighting in hospital design. Little information or guidance has been available to assist the development of a hospital's visual environment. A report on lighting and colour design schemes, accessible to non professionals with responsibility for refurbishment strategies, was required by NHS Estates. Firstly, 20 hospitals were audited to establish a picture of current practice and to identify key issues where colour design could broadly enhance the environment for patients, staff and visitors. Critical areas were outlined in this report, where colour design can be utilised and applied, for the benefit of all users, from ambience to essential legal requirements such as colour contrast for the visually impaired. Provision of staff relaxation rooms that are different in terms of colour and lux levels from immediate work spaces, or thoughtfully designed areas for patients awaiting intensive treatment, have been shown to have some beneficial effects on a sense of well being. Colour and design have not been established as a definite cure for sickness and ill health, but certainly monotony and poor conditions in premises that have not been refurbished with any care, have had a detrimental effect on recovery rates and staff morale. The realisation that a well balanced and attractive environment is of major importance to patients’ health is, in no way new; Florence Nightingale observed that ‘a variety of form and brilliance of colour in the objects presented to patients are an actual means of recovery’.
At last not least, Veitch  has been studied on light, vision and human mood and he conducted several tests on different type of lights. He investigated that the lighting quality is depended on three different elements. These elements are integration of individual well-being, economics and architecture. Clearly, the goal of creating high-quality lighting to improve organisational productivity is more challenging than the Hawthorne researchers realised when they changed workplace lighting by increasing the wattage of incandescent lamps. Good-quality lighting demands simultaneous resolution of requirements that sometimes conflict, and co-ordination with other building systems. Difficult or not, the effort is worthwhile, for in achieving this goal, everyone benefits. The following figure show how the light quality evaluated by integrating three different elements:
The purpose of this study is to test a new framework for understanding light as a design element. This paper described the development and validation of beliefs about the effects of common types of interior lighting on human health, work performance, mood, and social behaviour.
It will Study lighting in different spaces, both residential and commercial and users reactions to different type of lighting. In this research work, we studied several research articles to find the effects of interior lights in human mood and find that how the human reaction change by using different light design in different buildings.
In this way, the effect of lights based on colour and position is discussed such as lights in hospital, stores, office and residential sites. Moreover, we found that to integrating a light with high quality there are three important elements which the light and colour are take a place in one of these categories. In matter of fact, the interior lights can highly effect on social and communication, mood, comfort, health and safety and so on.
Study the other researchers work can clarify that these mentioned site effects are very important in human reactions such as study the interior light effects on hospitals, stores, etc. In addition, the light study show that the interior light design has different result on human behaviour based on gender, age or the place which they live in it. On the other hand, contrast between colours and lights can be very effective to suction people in stores or make more money in the entertainments.
Also, the combination of lights and colours and use them in right place can be cause to more pleasure and relaxation for people in one place such as restaurants and guestrooms or help them to decide or think better such as study room and dressing room. Study on interior lights taught us that the light direction and angle can effect mentally on space requirement on human mind.
Review other studies show that the lights also can affect on human communication and impressions. Finally, in this study few based and famous questionnaires which were designed by researchers to conducting few important tests on light effects is discussed.
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