Non-visual Effects Of Light Research Articles

Light exposure in the natural environment: Relevance to mood and sleep disorders

In addition to being necessary for vision, light also plays a primary role in circadian physiology. Humans are diurnal animals and their biological clock synchronizes their physiological functions in such a way that functions associated with activity happen in the daytime while functions associated with rest occur at night. A misalignment between the endogenous circadian clock and the desired sleep schedule is the main cause of circadian sleep disorders; it may be involved in certain mood disorders as well. Since light is the main environmental cue used by the biological clock to set its own timing in relation to the day–night cycle, inappropriate light exposure can be involved in the physiopathology of circadian disorders. Conversely, when handled properly, controlled light exposure can be used to treat some mood and sleep disorders. While the earliest studies in the field focused solely on exposure to bright light, contemporary studies aim at understanding how the entire profile of light–dark exposure can influence the circadian clock and, consequently, mood, sleep, and vigilance quality. Following a brief summary of the main concepts underlying the non-visual effects of light, this paper presents some studies using ambulatory measurements of light exposure to illustrate how these concepts apply in real-life situations and discusses the clinical relevance of light exposure in the natural environment for mood, sleep, and circadian disorders.

Considerations for lighting in the built environment: Non-visual effects of light

Light is defined as that part of the electromagnetic spectrum (∼380–780 nm) that gives rise to a visual sensation. Lighting in buildings, whether through use of daylight or by artificial means, is designed primarily for the visual needs of the occupants and their expected tasks within a given space. However, solar radiation, and, depending on spectral output of the source, artificial radiation, has other effects on human physiology and behaviour. Blue light affects the circadian rhythm, mood and behaviour; at shorter wavelengths in the ultraviolet (UV) the detriments of photoaging and sunburn are balanced by the benefits of Vitamin D synthesis.

A Healthy Future for Office Lighting?

For long standards and recommendations for office lighting are based on the horizontal illuminance at the working plane, this to ensure that the visual needs for a reading and writing task are fulfilled. Today, working in a modern office includes much more than just reading and writing. Working on a computer and communication with one or more persons have become the major tasks of an office worker. Thus the lighting requirements have to change too. That daylight is an important factor for a healthy and energy efficient office lighting has become widely accepted. Also knowledge has been obtained about the influence of light on mood and performance; apart from the visual system also the brain responds directly to light. Over the last decade research has been performed within Philips Lighting in Eindhoven, to obtain knowledge about the preference and acceptance of office lighting by the workers and about the non-visual effects of light on mood and performance.

Non-visual effects of light and colour : Kuller, R. Annotated bibliography. Swedish council for building research, Stockholm, Sweden, publication No. D15:81, 1981, 239 pp

Non-visual effects of light and colour : Kuller, R. Annotated bibliography. Swedish council for building research, Stockholm, Sweden, publication No. D15:81, 1981, 239 pp