Light has profound effects on our everyday functioning. It enables us to see, experience and interact with the world around us. Moreover, a large body of research has shown that light can affect our biological and psychological functioning through non-image forming processes. Many studies have shown that light is an important time cue for our biological clock, but can also induce acute alerting and activating effects. In this presentation, the effect of light on mental well-being and performance through both image-forming and non-image-forming pathways as well as implications for innovative lighting solutions will be discussed. Talk by Karin Smolders, Eindhoven University of Technology

1. Shining light on mental well-being
and performance
Karin Smolders
Human Technology Interaction & Intelligent Lighting Institute
Eindhoven University of Technology

2. Light and everyday functioning
• Artificial lighting has enabled us to turn on the light throughout
the 24-hour day
• Lighting is often used to perform tasks or create a pleasant
ambiance
• People are generally unaware of the potential impact of light on
their behavior and physiology in everyday life

3. Retinal light exposure and human functioning
Light not only enables vision, but is also important for our physiological
and psychological functioning

4. Retinal light exposure and human functioning
Light not only enables vision, but is also important for our physiological
and psychological functioning
Image-forming effects of light
- Visual performance
- Visual experience
Non-image forming effects of light
- Entrainment biological clock
- Acute effects mood, cognition, behavior

5. Newly discovered photoreceptor
Intrinsic photosensitive retinal ganglion cells
Non-image-forming
centers of brain
Image-forming
centers of brainLok (2011)

6. Enlighten our brain
Light
Intensity
Spectrum
Spatial
distribution
Timing
SC
N
Visual
Corte
x

7. Image-forming effects of light

8. Light and visual performance
Light enables us to extract and process relevant information to
engage in visual tasks
• Performance on visual tasks depends on lighting conditions, task
characteristics as well as a person’s age (e.g., see Boyce, 2003; Rea, 2000)
• Visual discomfort can hinder the visual system to extract information from the
visual environment
The lighting system should thus provide sufficient light to
support and optimize visual task performance, while
minimizing visual discomfort

9. Light and visual experiences
The light settings can influence employees’ appraisals of the
lighting and the ambient environment
Research has shown substantial inter- and intra-personal
variations in preferred light settings (e.g.,Begemann, van den Beld & Tenner, 1997;
Boyce, Eklund & Simpson, 2000; Butler & Biner,1987; Logadóttir & Christoffersen, 2008; Newsham, Aries, Mancini &
Faye, 2008)

10. Non-image-forming effects of light

11. Phase-shifting effects of light
Entrainment and phase-shifting biological clock
• Changes in the timing of sleep and wakefulness
• Alignment internal time to environmental demands
• Disturbances in sleep-wake cycles can affect well-being, health
and performance
• Jetlag, shift-work disorder or social jetlag
• Sleep disorder
• Seasonal affective disorder
Source: Is "9 to 5" a myth? Comstock/Getty Images

12. Light exposure at the edge of the night
Philips.co
m
sonymobile.com

13. Acute activating effects of light
Light can induce instantaneous changes in subjective
experiences, behavior and physiology via non-image forming
processes
• Exposure to more intense light may boost feelings of alertness and vitality
• Light intensity and spectrum may influence individuals’ ability to sustain attention and
cognitive performance
• Exposure to light at night can reduce melatonin secretion and affect the timing of sleep

14. Application of current insights
Lighting systems should not only meet visual and energy-
consumption requirements, but also incorporate individuals’
biological and psychological needs
Opportunities for innovative lighting systems to enhance
person’s wellbeing, health and quality of life in various
application domains

15. Application domains
Light can affect our functioning throughout the 24-h day, in
various application domains
OutdoorWorkplace
Schoo
l
Health care
Hom
e

16. Challenges for innovative lighting
Optimally tune lighting to the users‘ visual, biological and
psychological needs
Both image-forming and non-image-forming effects (as well as
potential trade-offs between these effects) should be
considered when designing lighting scenarios
Research suggest a potential for dynamic and intelligent
lighting solutions to provide the right amount of light (and
darkness) at the right time for a particular person

17. Thank you for your attention!
Rinko Kawauchi from