Proceedings of 1st International Symposium for Color Science and Art 2019

Investigation of Optimal Illumination Colorin Clinical Environment of Medicine
Tsuyoshi Moriyama, Takahiko Sakai, Akihiro Hasegawa*, Katsuyoshi Kasahara **,Naoshi Ogawa ***, Shun Nakamura ***, and Hiroshi Sasaki ****
Tokyo Polytechnic Univ., 1583 Iiyama, Atsugi, Kanagawa 243-0297, Japan* The Graduate School of Toyo Eiwa University, 5-14-40 Roppongi, Minato-ku, Tokyo 106-8507, Japan** Urata Clinic, 1-26 Hongo, Uozu, Toyama 937-0805, Japan*** EMBOSS Inc., 12-10-402 Chuo, Chigasaki, Tsuzuki-ku, Yokohama, Kanagawa 224-0032, Japan**** Ligare Chiropractic, YK Building 4th fl., 2-16-20 Minami-saiwai, Nishi-ku,Yokohama, Kanagawa 220-0005, Japan
standard for medical care[2].
We conducted anexperiment where the subjects executed memory orcalculation tasks under several illumination conditions thatvaried the illumination temperature and color to see how
the performance was affected.

ABSTRACT
We investigate the illumination condition in clinicalenvironment of medicine that could rather boost theefficacy of medical care. Medical care measures a personwith respect to the physical and mental performance in thefirst step that affects the entire process of medicine.
Despite the performance is known to be affected by theenvironmental factors, research efforts are not enough formaking it clear how to optimize the medical environment.
We conducted an experiment where the subjects
executed memory or calculation tasks under several
illumination conditions that varied the illumination
temperature and color to see how the performance wasaffected.

2. EXPERIMENTS
2.1 Memory task
Memorizing eight digits of numbers is commonly used
for memory task[3] whose process is depicted in Fig.1.
We change the illumination condition while the subject
repeat the memory task by following the protocol shown in
Table 1.
2.1.1 Illumination conditions
The subjects were set in front of a white screen withthe size 2,400mm x 1,800mm in a room without window.
The illumination was adjusted to 100 lx to be consistent
with conventional research.
Three illumination
temperatures 2,700K, 3,500K, and 6,200K wereswitched between the sessions of memory task.
2.1.2 Evaluating the score of memory task
Together with counting the correct answers, wecount the number and the timing of eye-blinking that isknown to be an indicator of memory process in brain
activity[4]. The correlative analysis between the scoreof memory task and the activity of eye-blinking wasdone.

1. INTRODUCTION
Humans have nature for adopting to their environment
and also keeping social balance with others by using all
their senses, i.e., vision, auditory, olfactory, gustatory, andtactile. From a different point of view, the environment
including other people that surround a person may change
the way of affecting him or her so that he or she could
extend the ability for doing tasks. Cheering at a sport
event is one of the examples where the audience plays therole of surrounding environment of a sport player that
could empower him or her by sending cheers. So is thecase in the clinical environment of medicine.
Recent hospitals pay much attention to theenvironmental issues such as the color of clothes of
medical staffs that to avoid threatening the clients by thescary stereotype of white clothes of medical doctors. The
color of room wall, curtains, devices, the position of lightsthat avoid being too bright to the clients under them, toname a few. Although they appear much better than
before, they almost base on the rule of thumb without any
scientific evidence so far that is a problem[1]. This work
aims at giving the evidence with regard to the illumination
conditions in medical environment by experiments.
In this paper, we focus on the cognitive measurementthat comes to the first place in medical process. The JIS
illumination standard is the standard for illumination for avariety of tasks that gives how bright the illumination
should be for each specific task. It, however, has noFig. 1 Block diagram of memory task

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Proceedings of 1st International Symposium for Color Science and Art 2019

illumination conditions while memory and calculation task
where the task scores were analyzed with respect to thecorrelation with biological metrics of heart-beat rate andeye-blinking rate which both were known to be correlatedwith neural activities.
The performance was also
correlated with the subjective evaluation of those tasks
using questionnaire.
Future work extends the results here that were obtainedin the experimental setups to real clinical environments.
One takes a communication task in the setting of clinicalpsychology, the other a preventive care for dementia in aregional private clinic.

Table 1 Protocol of the experiment on memory task.
timedescription
To-do
0:00
enter room, agreement,
and rest for 5 minutes
0:05
memory task w/ color1
0:05.1interval for a second
0:05.2
memorize numbers
8 numbers aredisplayed
every second
0:05.10 interval for 3 seconds
0:05.13 answer numbersanswer
thedisplayednumbers
inorderevery
second
0:05.21 interval for 2 seconds

Acknowledgement
This work was supported by “FY2016 MEXT Private
University Research Branding Project”.

repeat memory task 50 times
0:24.31
0:29.31

rest for 5 minutes
memory task w/ color2
rest
memory task w/ color3
rest

REFERENCES[1] Schweitzer, M., Gilpin, L., & Frampton, S., “Healingspaces: elements of environmental design that makean impact on health,” Journal of Alternative &Complementary Medicine, 10(Supplement 1), S-71
(2004).
[2] JIS Illumination Standard,
http://kikakurui.com/z9/Z9110-2011-01.html, (2010).
[3] Yamamoto, H., Shimizu, Y., “Change of pupil sizeand blinking time in memorizing numerals, “ Journalof the Institute of Television Engineers of Japan,
45(3):370-376, (1991).
[4] Nakano, T., “A New Role of Default Mode Network
Revealed by Eyeblink, “ Physiological psychology
and psychophysiology, 31(1):19-26, (2013).
[5] myBeat sensor, https://www.uniontool-mybeat.com/,
UNION TOOL CO..
[6] Takahashi K., and Inoue H., “A Quantitative Analysis
on Stress and Fatigue for VDT Workers Measured byHeart Rate Variability (HRV), “ Departmental Bulletin
Paper of Akita University, 30’1-7, (2009).
Fig. 2 Color conditions for calculation task.
2.2 Calculation task
The subjects calculate multiplication between two-digit
numbers over and over while switching three different
conditions of illumination. The protocol was similar to thememory task shown in Table 1.
2.2.1 Illumination conditions
The illumination was set as 100 lx with four colors ofred, green, blue, and white (illumination temperature
3,500K) as shown in Fig.2. The order of the illumination
conditions was randomized.
2.2.2 Subjective evaluation of calculation task
The subjects were asked to answer a questionnaire
in terms of “sleepy”, “easy”, “focused”, “relieved”,“relaxed”, “comfortable”, and “bored” in five steps for
rating.
2.2.3 Measuring biological metrics during the task
An electrocardiograph was measured during thecalculation task using the myBeat sensor[5] which
detected the heart-beat period as the parasympathetic
activity excited for calculating the mental load ofconcentration[6].
3. CONCLUSION AND FUTURE WORK
We conducted two kinds of experiments that varied38