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Light & Health - Design Strategies & Technologies February 12, 2015

Konstantinos Papamichael, Ph.D. Professor, Department of Design Co-Director, California Lighting Technology Center University of California, Davis

The Main Source of Light & Life

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The Sun

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Spectral Distribution of Sunlight

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The Electromagnetic Spectrum

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Daylight Spectral Power Distributions

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The Dynamic Nature of Daylight

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Daylight Spectral Power Distributions

8http://www.handprint.com/HP/WCL/color1.html

Daylight Correlated Color Temperature (CCT)

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http://www.lrc.rpi.edu/programs/nlpip/lightinganswers/fullspectrum/comparisons.asp

Human Evolution - Sunrise

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Human Evolution - Daytime

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Human Evolution - Sunset

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Human Evolution - Night

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Human Evolution - Light at Night

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Human Evolution - Light at Night

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Visual & Circadian Pathways

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1. Visual Pathway

– Light stimulates the cerebral

cortex for vision & perception

2. Biological Pathway

– Light causes messages

along a biological pathway

(Hypothalamus, Pituitary,

Pineal Gland) that are used

to regulate the body’s

autonomic nervous and

endocrine systems

Human Eye Anatomy

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Cornea!Aqueous Humor!

Pupil!

Iris!

Ciliary Muscle!Sclera!

Fovea!

Retina!

Optic Nerve!

Vitreous Humor!

Eyelens!

Choroid!Suspensory ligament!

Retinal Structure

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Rods (Rhodopsin) & Cones (Photopsins)

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Photopsin & Rhodopsin Sensitivities

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http://www.handprint.com/HP/WCL/color1.html http://hyperphysics.phy-astr.gsu.edu/hbase/vision/bright.html

ipRGC (Melanopsin) intrinsically photosensitive Retinal Ganglion Cell

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•  Photo pigment

•  Specialized ganglion cells

•  Biological path

•  Circadian rhythms

•  Pupillary reflex

• Specialized ganglion cell

• Many & long tentacles

• Melanopsin photopigment

• Biological path

• Circadian Rhythms

• Pupillary (+?) control

Adaptation Mechanisms

• Mechanical change: pupil diameter

– Admits varying amounts of light

– Factor of about 5%

• Photochemical change: changing amounts of photo pigments available

– Bleaching makes less pigment available

– Factor of about 1000%

• Neural change: changing synaptic interaction

– Lower overall neural sensitivity as light level increases

– Factor of about 1000%

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Photopic, Scotopic & Circadian Sensitivities

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Circadian Rhythms

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• Endogenous (self-sustained) rhythms • From the Latin

– “circa” = approximately – “dies” = day

• Have been observed even in single celled organisms including prokaryotes, e.g,. bacteria

• Major Biological Effects – Hormone Excretion

• Melatonin - sleep-wake cycle • Insulin - carbohydrate metabolism • Cortisol - blood pressure & sugar levels

– Body Temperature – Cognitive performance – ...

Melatonin & Cortisol Circadian Rhythms

Incandescent Spectral Power Distribution

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Pros & Cons of Incandescent Lighting

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• Pros – Excellent color rendering - 100 CRI – Excellent for well-being & health - low blue content – Excellent dimming - smooth, further reducing blue content – Excellent drama - sharp shadows – No flicker! – No noise! – Low cost

• Cons – Low luminous efficacy

Fluorescent Lighting CCT (K)

2700 3000 3100 3500

3500 4100 5000 6500

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Fluorescent Spectral Power Distribution

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Natural Daylight

Incandescent Daylight Fluorescent

Cool White Fluorescent Tri-Phosphor 3500K

Metal Halide

Spectral Power Distributions

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Photopic Illuminance: 2 fc - Scotopic Illuminance: 200+ fc

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UC Davis Medical Center Sign

Photopic, Scotopic & …Cirtopic? Lumens

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2

200

?

Blue-rich Light at Night

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American Medical Association - June 2012

Light  Pollu+on:  Adverse  Health  Effects  of  Nigh;me  Ligh+ng    Report  4  of  the  Council  on  Science  and  Public  Health  (A-­‐12)  of  the  American  Medical  Associa/on  

Biological  adapta+on  to  the  sun  has  evolved  over  billions  of  years.  

The  power  to  ar+ficially  override  the  natural  cycle  of  light  and  dark  is  a  recent    event  and  represents  a  man-­‐made  self-­‐experiment  on  the  effects  of  exposure  to  increasingly  bright  light  during  the  night  as  human  socie5es  acquire  technology  and  expand  industry.    

Among  the  la;er  (health  effects)  are  poten5al  carcinogenic  effects  related  to  melatonin  suppression,  especially  breast  cancer.  Other  diseases  that  may  be  exacerbated  by  circadian  disrup5on  include  obesity,  diabetes,  depression  and  mood  disorders,  and  reproduc+ve  problems.  

Due  to  the  nearly  ubiquitous  exposure  to  light  at  inappropriate  +mes  rela+ve  to  endogenous  circadian  rhythms,  a  need  exists  for  further  mul+disciplinary  research  on  occupa5onal  and  environmental  exposure  to  light  -­‐at-­‐night,  the  

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Blue-rich LED & Circadian Sensitivity

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Key Lighting Design Strategies for Health

• Reduce exposure to blue light during the night – Outdoor lighting

• Luminaires • Signage

– Indoor lighting - especially residential • Luminaires • Televisions • Computer displays

• Increase exposure to blue light during the day – Daylight! – High CCT light sources for applications that need it

• Offices • Schools • Work spaces • Assisted living housing

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Implementation Strategies & Technologies• Outdoor Lighting

– Occupancy-based bi-level lighting • Single Source

– Full output during occupancy – 50% or less during vacancy (10% - 20% is enough)

• Dual Source – High level Low CCT white light during occupancy – Low level Amber or Amber-Red LED during vacancy

• Indoor Lighting – Nighttime

• Low CCT (less than 3,000k) • Low level Amber or Amber-Red LED for nightlight

– Kitchen – Bathroom – Way finding

– Daytime • Daylight! • High CCT lighting - for applications that need it

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High CCT Lighting for Offices & Schools

• Mills, Peter R., Tomkins, Susannah C. and Schlangen, Luc JM. “The effect of high correlated colour temperature office lighting on employee wellbeing and work performance.” Journal of Circadian Rhythms, 11 January 2007, pages 2-5.

• High CCT Electric Lighting in Call Center with Shift Work

• Reduced fatigue (26.9%) • Increased alertness (28.2%) • Reduced daytime sleepiness (31%) • Increased work performance (19.4%) • Increased vitality (28.4%) • Increased mental health (13.9%)

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Melatonin Suppression

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446 477

Brainard, George C. “Action Spectrum for Melatonin Regulation in Humans: Evidence for a Novel Circadian Photoreceptor.” The Journal of Neuroscience (2001): 6405-411. Web. 29 Apr. 2013.

Monochromatic LED Spectra Manufacturer A

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446 477

400 550

400 550

Monochromatic LED Spectra Manufacturer B

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446 477

Effective

Most Effective

Bathroom Light Switch with Occupancy Sensor & Amber LED Night Light

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Dual Source Bi-level Outdoor Luminaire

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Amber LED & Induction Lighting

Dual Source Bi-level Outdoor Luminaire

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Occupancy Mode

Dual Source Bi-level Outdoor Luminaire

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Vacancy Mode

Indirect Downlight Prototypes

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Dual Source Kitchen Lighting

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Full Light Output Night Lighting - Amber LEDs

Spectrally Tunable Lighting for Office Spaces

• Laboratory Prototype • Independent control of

– Intensity – CCT

• Change CCT maintaining Intensity • Change intensity maintaining CCT

WA

RM

NE

UTR

AL

CO

OL

100% 50% 25%

Refrigerator Lighting

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White Light Amber Light

HONDA ZNE House, UC Davis

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Honda House - First Floor Amber LED Way Finding Night Lighting

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Honda House - Second Floor Amber LED Way Finding Night Lighting

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Bathroom & Kitchen Lighting

Amber LED “Toe-Kick” Night Light

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Amber LED “Toe-Kick” Night Light

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Kitchen Amber LED Night Lighting

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Kitchen High & Low Amber LED Night Light

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Living Room - High & Low Ambient Lighting

Corridor Lighting

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Stairwell & Corridor Night Lighting

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De Young ZNE House, Fresno, CA

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Bathroom Lighting

Kitchen Lighting

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Corridor Lighting

Maximizing Health & Sleep in the Elderly LD+A Article by Kimberly Mercier

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Philips “Heu” Screw-based Lamp

66DigitalTrends.com

Wireless Base - Hardwired to Wi-Fi Router

67DigitalTrends.com

“Relax” Setting

68DigitalTrends.com

“Concentrate” Setting

69DigitalTrends.com

“Reading” Setting

70DigitalTrends.com

Philips “Hue” Screw-based Lamps

71DigitalTrends.com

6000K, 100fc average 3500K, 50fc average 2900K, 50fc average

Photo credit: Philips

5000K  -­‐  Focus/Concentrate  6500K  -­‐  Wake  Up/Morning  4000K  -­‐  Group  Ac5vity  3000K  -­‐  Relax  

Philips Circadian Lighting for Classrooms

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12000K, 65fc average

Samjin Color-Tunable Lighting

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50%

100%

2700K 4000K 6500K

BRIG

HTNESS

CCT

SAMJIN

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RESEARCH INNOVATION PARTNERSHIP 633 Pena Drive, Davis, CA, 95618 | cltc.ucdavis.edu | PH: 530-747-3838, FAX:530-747-3812

Thank You!

kpapamichael@ucdavis.edu