Shining light on mental well-being and performance

Karin Smolders

Human Technology Interaction & Intelligent Lighting InstituteEindhoven University of Technology

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

Retinal light exposure and human functioning

Light not only enables vision, but is also important for our physiological and psychological functioning

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

Newly discovered photoreceptor

Intrinsic photosensitive retinal ganglion cells

Non-image-forming centers of brain

Image-forming centers of brainLok (2011)

Enlighten our brain

Light

IntensitySpectrumSpatial distributionTiming

SCN

Visual Corte

x

Image-forming effects of light

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

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)

Non-image-forming effects of light

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

Light exposure at the edge of the night

Philips.com

sonymobile.com

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

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

Application domains

Light can affect our functioning throughout the 24-h day, in various application domains

OutdoorWorkplace

School

Health care

Home

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

Thank you for your attention!

Rinko Kawauchi from 'Illuminance'