anagha ajaykumar research presentation - healthy lighting systems

The impact of job characteristics on the health benefits of healthy lighting systems in workplaces

Presented by: Anagha Ajaykumar

Supervisor: Dr. Wendy Davis

Visual and non –visual impacts of

light

Adverse effects of

artificial lightLab studies

Current healthy Lighting Systems

Field tests

Possible factors of impact

Factors in focus

Aim & Hypotheses

Research methodology

Discussion & Conclusion

Visual & non visual impacts of light

Visual function:

• Image forming

• From rods and cones in the retina to the

visual cortex in the brain

• Depends mostly on amount of light entering

the eye.

Neural pathways (van Bommel & van den Beld, 2004).

Visual and non – visual impacts of light

Adverse effects of artificial light

Lab studiesCurrent healthy

Lighting Systems

Field testsPossible factors

of impactFactors in focus

Aim & Hypotheses


Discussion & conclusion

Non - visual function:

• Mediates photo biological functions

• From the Intrinsically Photosensitive Retinal

Ganglion Cells (ipRGCs) to the Super

Chiasmatic Nuclei (SCN)

• Depends on

• Time of exposure

• Illuminance

• CCTNeural pathways (van Bommel & van den Beld, 2004).

Visual & non visual impacts of light




Lighting Systems



Aim & Hypotheses



Photo biological impacts

• Stabilizing Core Body Temperature (CBT)

• Alertness

• Circadian rhythm

• Heart rate

• Hormonal production

• Melatonin (sleep hormone)

• Cortisol (stress hormone)

(van Bommel & van den Beld, 2004)

Natural rhythm of hormonal production under 24 hr natural light cycle (van Bommel,

2006).




Lighting Systems



Aim & Hypotheses




• Static illuminance and CCT levels

• Overexposure

• Disrupts melatonin secretion

• Causes circadian phase shift

• Sleep impairment

• Disrupts Cortisol secretion

• Increases tiredness

• Start of fatigue

(Aries, 2005)

24 hr cortisol cycle . Image from: https://www.integrativepro.com/Resources/Integr

ative-Blog/2014/The-Role-of-Cortisol.aspx




Lighting Systems



Aim & Hypotheses



Fatigue in the workplace

Excessivework

demands

Exhaustion of personal resources

Fatigue Absenteeism

Static artificial lighting




Lighting Systems



Aim & Hypotheses



Lab studies

• Studies show indirect co relation between bright light (5000 lx) and fatigue levels.

• This effect is independent of the time of day of exposure (Ruger et al., 2005)

• Also Independent of eye correction, chronotype (sleep habits) and other individual characteristics (Aries M., 2005).

• Lower fatigue levels are observed under dynamic lighting (500 – 1800 lx), varying in 30 min intervals, compared to static lighting (500 lx for 8 hrs) (Hoffmann et al., 2008).

Course of subjective fatigue levels through day (left) and night (right) time exposure of

bright & dim light. (Ruger et al., 2005)



Lab studies




Aim & Hypotheses



Current Healthy Lighting Systems



Lab studies




Aim & Hypotheses



Image from http://humancentriclighting.com/wp-content/uploads/2012/07/Stan-Article-SSL1.pdf

• Develop healthy lighting systems for:

• Schools

• Workplaces

• Health centers

• Domestic environments

• Claims to improve user:

• Health and well being,

• Task performance

• Need for recovery

• Need for recovery: is that feeling of exigency to take a breather from current demands. It marks the beginning of fatigue and therefore has a direct correlation with it (Sonnentag & Zijlstra, 2006).

("Lighting For People – web-based platform for high quality information on solid state lighting in Europe", 2016) & (Humancentriclighting.org, 2014)

Top & middle: Lightingforpeople logo. Image from: http://lightingforpeople.eu/.

Bottom: Human centric lighting society logo. Image from:

http://humancentriclighting.com/wp-content/uploads/2012/07/Stan-Article-

SSL1.pdf

Current Healthy Lighting Systems



Lab studies




Aim & Hypotheses



http://lightingforpeople.eu/

Field studies

• Dynamic lighting patterns have been

employed in workspaces and their

effects observed.

• Measurements where made on the

claimed health benefits:

• Need for recovery

• Alertness & vitality

• Sleep quality

• None of the claimed benefits where

observed, that was significant

enough to be considered.

(de Kort & Smolders, 2010) Dynamic lighting pattern employed by de Kort & Smolders, 2010.




Lighting Systems

Field tests


Factors in focusAim &

HypothesesResearch

methodologyDiscussion & conclusion

Within person Sleep quality

Health

Fatigue

Job characteristics

Job demands

Job control

Off – job activities

Amount of time spent in job related activities

Amount of time spent in household and child care activities

Amount of time spent in leisure activities

Experience quality





Lighting Systems

Field tests


Factors in focusAim &

HypothesesResearch

methodologyDiscussion & conclusion

Factors in focus




Lighting Systems


of impact

Factors in focus

Aim & Hypotheses



Job demands

Drastic working situations

OvertimeWork under

pressure

Time constraints

Job demands:

• Direct correlation has been observed

between job demands and need for

recovery levels (Sonnentag et al.,

2006).

Job control:

• Is the autonomy of the individual on

his/her task for:

• Taking breaks,

• Composing one’s own method of working and

• Ability to rearrange schedules to suit their convenience.

• A negative correlation has been

observed between job control and need

for recovery.

(Jackson, Wall, Martin, & Davids, 1993).

Job control

Job demand

Need for recovery

Fatigue

+

-

+

Factors in focus

Healthy Lighting Systems

-




Lighting Systems


of impact

Factors in focus

Aim & Hypotheses



Aim of the proposal




Lighting Systems



Aim & Hypotheses



Aim: A field study is proposed here that would aim to compare the need for recovery

levels of a varied group of employees with different combinations of job demand and

control levels under dynamic versus static lighting conditions.

Hypotheses

Job control

Job demand

+ =

Job control

Job demand

+ =

Job control

Job demand

+ =N N

Health benefits of HLS






Lighting Systems



Aim & Hypotheses







Lighting Systems



Aim & Hypotheses



1. Study group:

a) A large group of subjects (n ≥ 100).

b) In varying job positions and responsibilities.

c) Job demand and control levels to be measured for each individual, prior to beginning study.

d) Employees to be grouped according to job demand and control levels.

Me

Job demand

Job control

Job demand

Job control

Job demand

Job control

Job demand

Job control

Job demand

Job control

N

Job demand

Job control

N

Job demand

Job control

NN

1.1 Measuring job demands:

a) Via self – administered questionnaire

b) Questions adopted form Job Content Questionnaire (JCQ) (Karasek et al., 1998)

1.2 Measuring job control:

a) Via self – administered questionnaire

b) Questions from Dr. Greenbergers’ report on “Personal control at work” (1981).

A. My job requires me to work fast:

Strongly disagree

Somewhat disagree

Neutral

Somewhat agree

Strongly disagree

A. I have control over my schedule:

Strongly disagree

Somewhat disagree

Neutral

Somewhat agree

Strongly disagree





Lighting Systems



Aim & Hypotheses



2. Study period:

a) To be conducted in darker winter months (July – August)

3. Study methodology:

a) Study group can be divided into 2.

i. Both groups should be in identical office spaces.

b) Each group can be exposed to the two lighting conditions alternatingly for a period of 2 weeks each.

i. Total 4 weeks

c) Subjects fill out the ‘need for recovery’ questionnaire at the end of the day, before bed – time.

WEEK 1 & 2

A B

WEEK 3 & 4

A B





Lighting Systems



Aim & Hypotheses



4. Measuring need for recovery levels:

a) Questions adopted from ‘Need for recovery’ scale (van Veldhoven et al., 2003)

5. Lighting settings:

a) Same dynamic lighting pattern as employed by de Kort (2010)

b) Tunable LEDs controlled via central control module.

c) Same luminaires to be used under static conditions.

A. I found it hard to unwind tonight by bedtime:

Yes

No

Dynamic lighting pattern employed by de Kort & Smolders, 2010.





Lighting Systems



Aim & Hypotheses



• Data analysis:

• Regression analysis to be done to

identify correlations between job

characteristics and need for recovery

levels.

• Possible results:

• For those who are already under great work pressure, lighting changes might go unnoticed and might render futile.

• Might be effective in enhancing the work experience of the relaxed employee.

I don’t care anymore





Lighting Systems



Aim & Hypotheses



Employee number

Phase 1 Phase 2

Week 1

Week 2

Week 3

Week 4

Static

Employee 1

xx xx

Employee 2..

Dynamic

Employee 3

Employee 4…

Table to input data on need for recovery levels of different employees throughout the period of the

study and under different lighting conditions





Lighting Systems



Aim & Hypotheses



• Proposed methodology can also be used to

study impacts of lifestyle parameters.

• This experiment would just be an initial

contributor to many more studies to come,

in learning to optimize Healthy Lighting

Systems.

Off – job activities

Amount of time spent in job related activities

Amount of time spent in household and child care activities

Amount of time spent in leisure activities

Experience quality

Key references

• van Bommel, W., & van den Beld, G. (2004). Lighting

for work: a review of visual and biological

effects. Lighting Research And Technology,

36(4), 255-269.

• Aries, M. B. C. (2005). Human lighting demands:

healthy lighting in an office environment.

Technische Universiteit Eindhoven, Faculteit

Bouwkunde.

• Hoffmann, G., Gufler, V., Griesmacher, A., Bartenbach,

C., Canazei, M., Staggl, S., &

Schobersberger, W. (2008). Effects of

variable lighting intensities and colour

temperatures on sulphatoxymelatonin and

subjective mood in an experimental office

workplace. Applied Ergonomics, 39(6), 719-

728.

http://dx.doi.org/10.1016/j.apergo.2007.11

.005

• Ruger, M. (2005). Time-of-day-dependent effects of

bright light exposure on human

psychophysiology: comparison of daytime

and nighttime exposure. AJP: Regulatory,

Integrative And Comparative Physiology,

290(5), R1413-R1420.

http://dx.doi.org/10.1152/ajpregu.00121.

2005

• Humancentriclighting.org. (2016). Human Centric

Lighting. [online] Available at:

http://humancentriclighting.org/

[Accessed 25 May 2016].

• Lighting For People – web-based platform for high

quality information on solid state lighting

in Europe. (2016). Lightingforpeople.eu.

Retrieved 22 May 2016, from


http://dx.doi.org/10.1016/j.apergo.2007.11.005

http://dx.doi.org/10.1152/ajpregu.00121.2005


THANK YOU