Human Centric Lighting - beyond our eyes: the non -visual impact of light Christian Cajochen, PhD Centre for Chronobiology Psychiatric Hospital of the University of Basel, Switzerland
European Lighting Summit, Brussels, 30.03.2017 Thomas Edison was probably wrong
Light is the most important Zeitgeber !
Buttgereit, Smolen, Coogan, Cajochen, Nat Rev Rheumatol, 2015 Light and human circadian rhythms Melatonin as the best circadian marker in humans
Induction of a Phase Delay in the Human Circadian Melatonin Rhythm by Light (10’000 lux for 6.5 h)
Midpoint Midpoint 4:45 8:21
400
Light /L)
300 pMol
200
100 Plasma Melatonin ( Melatonin Plasma 0 12 24 12 24 12 24 12 24 12 Time of Day
Sleep period Khalsa et al., J Physiol (London) 2003 Light and circadian phase
Phase-Response Curve
4 3
2 (h) 1 shift 0
-1 Phase Phase -2
-3 6.7 hours 10’000 lux -4 polychromatic whiteRetina light -18 -15 -12 -9 -6 -3 0 3 6 9 12 15 18 Initial Phase (time relative to DLMO=0)
Khalsa, et al., J Physiol (London) 2003 «Light impacts on our circadian rhythms more powerfully than any drug»
Charles Czeisler «Casting light on sleep deficiency» Nature, 2013 Suppression of melatonin in a totally blind person with bright light
Sighted Person 300
200 Plasma Melatonin 100 (pmol/liter)
37.5
37.0 Core Body Temperature 36.5 (°C)
36.0 12 18 24 6 12 18 24 6 12 Time of Day (h) Blind Person 300
200 Plasma Melatonin 100 (pmol/liter)
37.5
37.0 Core Body Temperature (°C) 36.5
36.0 12 18 24 6 12 18 24 6 12 Time of Day (h) Czeisler et al., New Engl Med 1995 Light is more than vision non-visual / non-image forming light effects
Light can be «seen» without conscious vision
«Forced choice» test in a totally blind person
100 *
80
60
40
Correct Answer (%) 20
0 420 460 481 500 506 515 540 560 580 Wavelength (nm)
Nach Zaidi et al., Curr Biol, 2007 Non-classical Photoreceptor intrinsic photosensitive retinal ganglion SCN cells (iPRGs, Melanopsin) (circadian Pacemaker)
Eye A dual sensory organ
Rods
Retina Cones
Hattar et al. Science, 2002 Berson et al. Science, 2002 Light and circadian phase Phase-Response Curve
4 3
2 (h) 1 shift 0 -1 Phase Phase 75 % of the resetting -2 response
-3 6.7 hours 10’000 lux -4 polychromatic whiteRetina light 6.5 hours blue light (480 nm) -18 -15 -12 -9 -6 -3 0 3 6 9 12 15 18 11.8 μWcm−2, 11.2 lux) Initial Phase (time relative to DLMO=0)
Khalsa, et al., J Physiol (London) 2003 Rüger, et al., J Physiol (London) 2013 Acute sleep induction by light in nocturnal mice
Lights ON Lights OFF 60 Wildtype Melanopsin knockout
Melanopsin aDTA
30
Response (min) Response
Sleep
0 0 1 2 3 Time elapsed from light onset (h)
According to Muindi et al., Front Syst Neurosci, 2014 Acute alerting effects of light in diurnal humans Subjective Alertness
5
10
more alert more 15
20
120 lux !
25
10 100 1000 10000
Illuminance (lux) Cajochen et al., Beh Brain Res. 2000 Karolinska Sleepiness Scale (KSS) 8 6 7
Monochromatic The human
light alerting
% Sleepiness Change
0 = pre-light response 10 20 30 40 50 Energy 0
Saving
to Book chapter, Book Springer,2014 et alCajochen
Lamps
light
is ., Sleepiness and human impact impact assessmenthumanSleepiness and .,
blue
Karolinska Sleepiness Scale (KSS) - 4 5 6 shifted
Computer Screens
Declarative Learning (Word pairs)
Correctly identified new word pairs
70 * 65
60
55
50
45
* P <0.05 LED Screen Non-LED Cajochen et al., J Appl Physiol. 2011
Why is this relevant: Light bulb versus LED
Relative Contribution Relative
Wavelength (nm)
Relative Contribution Relative
Wavelength (nm) Smartphone use in adolescents (14-20 years)
Use of smartphones Where do you keep your smartphone during night? 1 hour prior bedtime
irgendwo in der Wohnung 14% 23% irgendwo im Zimmer 99 % Ja auf dem Nachttisch nicht beantwortet im Bett 60% 99% yes nicht beantwortet
97% in bedroom How often do you use your smartphone after «Lights off»
10% nie 15% selten 49% gelegentlich häufig 25% nicht beantwortet Strube et al. Somnologie, 2016 74% occasionally-often “Ipad” versus “Blue-blockers” Transmission Spectra
1.0
0.8
0.6
0.4
0.2 Relative Amplitude Relative
0 400 450 500 550 600 650 700 Wavelength iPad Orange-tinted glasses (blue blockers) Evening Melatonin Levels in Adolescents
Dim Dark LED/glasses Dim
* Blue Blockers for one week 16 Clear Lenses for one week 14 * * 12
*
10
8
pg/ml Sleep 6
4
2
0
Time of day
van der Lely et al., J Adolesc Health, 2014 KSS-score 2 3 4 5 6 7 8
*
Subjective Sleepiness in Adolescents Dim Blocking blue light intheevening
Dark
LED/glasses Time of of day Time *
* Sleep Sleep Dim van2014 Health, Lely Adolesc etJ der al.,
Clear Lenses for week one Clear Lenses Blue Blockersfor Blue week one
Light is not just for vision
Cortex Thalamus Hypothalamus Brainstem - Locus coeruleus
Limbic system - Amygdala - Hippocampus
Modified from Vandewalle et al. Trends Cogn Sci, 2009 Light has many non-visual biological effects in humans (only peer reviewed data)
• Synchronization of circadian rhythms
• Suppression of the «darkness hormone» melatonin
• Alerting and enhancing of cognitive performance
• Regulation of pupil size
• Enhancing mood (antidepressant)
• Enhancing physical performance in top athletes
• Light color modulates mental effort
Conclusion
• Light rules our body via its non-visual effects
• Blue wavelengths -- which are beneficial during daylight hours because they boost attention, reaction times, mood, and physical performance -- are most disruptive at night
• The proliferation of electronics with screens, as well as energy-efficient lighting, is increasing our exposure to blue wavelengths, especially after sundown Non-visual lighting solutions should be:
Dynamic • Intensity and duration • Spectral composition • According to time of day
Individual • Age • Gender • Chronotype (early vs.late people) Conventional LED vs. daylight LED
Daylight LED Conventional LED Blue is not blue
1.2 Conventional LED 1.0 Daylight LED
0.8
0.6
0.4
Arbitrary Unit Arbitrary
0.2
0.0 The same photopic lux: 100
360 390 420 450 480 510 540 570 600 630 660 690 720 750 780 and the same colour temperature: 3700 K Wavelength (nm) for both light conditions
0.5
0.4 Difference melanopic lux Intensity Intensity [m-lx] 0.3 illuminance power density 2 or 0.2 [lx, phot.] [mW/cm ] [z-lx]
0.1 Daylight LED 67.9 Arbitrary Unit Arbitrary 0.0 97 0.037
-0.1 Conv. LED 98 0.029 56.9 -0.2
-0.3 360 390 420 450 480 510 540 570 600 630 660 690 720 750 780
Wavelength (nm) Conventional LED vs. daylight LED
Baseline Treatment Conv. LED Night Night
18 22 24 8 10 14 18 22 24 8 10 14 18 22 Time of day
Baseline Treatment Cognitive Test Battery Night Night Daylight LED 10 14 18 22 18 22 24 8 10 14 18 22 24 8 10 14 18 22
Subjective Rating of Light Quality (Brightness and Colour Temperature) 5.0 *
4.5
The same photopic lux: 100 and the same colour temperature: 3700 K 4.0 for both light conditions
Light Quality Light
3.5
Conv. LED
worse better Daylight LED 3.0 Wanted
Intelligent human centric lighting to adapt our illuminated surroundings such that we do not jeopardize quality of life and health but positively influence our sleep, circadian physiology, cognition and well-being
Human Centric Lighting
enter the room by
Human centric lighting supports your health and promotes Acknowledgements Centre for Chronobiology • Antoine Viola, PhD • Sarah Chellappa, PhD • Virginie Gabel, PhD • Mirjam Münch, PhD • Vivien Bromundt, PhD • Van der Lely, MS • Sylvia Frey, PhD • Doreen Anders, PhD • Weibel, Janine, MS • Basishvili, Tamar, PhD • Christina Schmidt, PhD • Micheline Maire, PhD • Carolin Reichert, PhD • Jakub Späti, PhD
Fraunhofer Institute • Oliver Stefani
EU IP Swiss Federal Office for Public Health Daimler-Benz Foundation