Single person experiments with light

A romantic dinner by candle light, bright lights in an office building. Both give us a very different experience. We all know from experience how light can influence our mood and the way we perceive a space.
What I want to find out with Meditation Lab is if light conditions can also influence the quality of your meditation experience. I have a hunch that it does. This is also based on over 20 years of daily meditation practice. And I’ve found starting points on optimal lighting during meditation in scientific research.

Building a meditation lab in my attic

Building a meditation lab in my attic

Conditions for a good meditation session

Contrary to a commonly held belief meditation isn’t about being relaxed and a little sleepy. I practice in the Buddhist tradition of Vipassana (insight) meditation. This form of meditation is about being fully present in the moment without effort. This clear observation will give a person insight into the true nature of reality. This insight will help to overcome suffering and to become a wiser and more compassionate being. An important concept in this context is the Satipatthana.
So the ideal state for a good meditation session is being relaxed but at the same time alert. I had heard about changing light conditions in classrooms to support different activities and states of mind of students. I was also wondering if work had been done on the psychological aspects of light. I’ll summarize my findings and tell about how I will be translating that into one person experiments.

Working with a light expert

Before diving into the theory I would like to explain how I will go about changing the light conditions. I was very fortunate be introduced to Tom Bergman. He is Principal Scientist at Philips Lighting. He has been working on what he calls Light instruments: LED light systems that can be programmed and played like a musical instrument. With his instruments he wants to go beyond mere functionality and use light for expression and experience. Our goals and explorations were a perfect match. I will be using his 9 x 9 mosaic instrument. It can make all colours and make beautiful and unexpected colour transitions. Also interesting is that it has been tested as tool for relaxation by master student Nina Oosterhaven (1). Her study showed for example that looking at changing patterns of light showed a significant reduction in heart-rate. So there are interesting starting points to work with the instrument.
The light instruments are of course very specialized and not commercially available. So Tom kindly also supplied me with a Philips Hue Go. This will enable me to try out similar settings with a consumer device which is already Internet of Things ready.

The lab set up: Light instrument, meditation mat and data server

The lab set up: Light instrument, meditation mat and data server

Types of light

Psychological effects

In the various articles I read I was looking for settings in light colour and intensity that would either relax or activate people and make them alert. There hasn’t been much research on the psychological effects of lighting. Seuntiens and Vogels(2) have done research on atmosphere and light characteristic in living room settings with a group of light designers. They looked at four types of atmospheres of which activating and relaxing are relevant for Meditation Lab. Interesting were their findings on the influence of colour temperature, brightness and dynamics on these atmospheres. In general the findings were: warmer (+/- 2700 Kelvin), static and less bright light (180 lux) is perceived as relaxing. Cooler (+/- 3800 K) and brighter light (390 lux) is perceived as activating this light can have a slow dynamic.

School performance

Sleegers et al (3) looked at school performance in children and students under adjusted light conditions. Their studies used build in light systems which had different settings. Focus, calm and engery are the most interesting for my project. Energy is an interesting setting, it is used in the morning or after mealtime to overcome sluggishness. The settings correspond with the following light properties (measured at eye-hight):
Energy:650 lux and 12000 K colour temperature
Focus:1000 lux and 6500 K colour temperature
Calm:300 lux and 2900K

Staying awake

Jacques Taillard et al (4) studied the effects of blue light on staying awake whilst driving a car at night. They compared the effects of continuous blue light to drinking coffee. When compared to a placebo both coffee and the blue light condition reported significantly less inappropriate line crossings with coffee doing only slightly better then blue light. The light source was a Philips GOLite with a wavelength of 468 nm. Luminance level was around 20 lux measured at eye level.

Research design

Sleepiness, tension and lack of focus are challenges you face when meditating. By experimenting with different types of light I want to find out if the findings in other areas can be used in a meditation setting. I will use warm white light for relaxation, cool white light for focus and blue light for alertness. I will be exposed to one light condition per 20 minute meditation session. Before and after every session I fill in the standardised questionnaires which I have designed. I have started single person experiments (n=1) and I have designed the following experiments.

Design single person experiments

Design single person experiments

There is no baseline measurement included in the single person meditation session. Instead I have conducted 54 baseline session under my usual meditation conditions. I did a 6 day solitary retreat at home. The sessions took place throughout the day, I didn’t manipulate anything, especially not the light conditions. So they varied widely as the day progressed.

Current findings

At the moment I’m conducting n=1 experiments using the Light instrument and the three main light states described above. I’ve set up a darkened lab to control the light conditions. I keep my eyes slightly open with my gaze turned down.
My first impressions are that there is a difference from what I normally experience during meditation. The white lights I find quite relaxing and somehow invigorating. The blue light I find less pleasant and a bit depressing. I suppose the light will interact with my overall state of focus, sleepiness and alertness as it fluctuates during the day. That is why I try to do the experiments at different times of the day while using the same light setting. I do worry a bit about my sleep when meditating in the evening in bright light. For that reason I have turned down the brightness (there a 5 settings) in an effort to not affect my sleep too much.

The single person experiments are my starting point. Later I will report on my design for group experiments. I’m always on the lookout for people who would like to join the experiments. So please leave a comment if you want to participate.

1) Oosterhaven, N. (2017). Fascinated by Dynamic Lighting. Thesis Master of Science In Human Technology Interaction
2) Seuntiens, P.J.H. & Vogels, Ingrid. (2008). Atmosphere creation: The relation between atmosphere and light characteristics. Proceedings from the 6th Conference on Design and Emotion 2008.PJC Sleegers, PhD, NM Moolenaar, PhD, M Galetzka, PhD, A Pruyn, PhD, BE 3) Sarroukh, PhD, B van der Zande, PhD (2013). Lighting affects students’ concentration positively: Findings from three Dutch studies. Lighting Research & Technology Vol 45, Issue 2, pp. 159 – 175
4) Taillard J, Capelli A, Sagaspe P, Anund A, Akerstedt T, Philip P (2012) In-Car Nocturnal Blue Light Exposure Improves Motorway Driving: A Randomized Controlled Trial. PLoS ONE 7(10): e46750.

Virtual View: experiment 3 setup

For the design of the third experiment I got advice from Petra van der Schaaf, environmental psychologist. The main research question for this experiment is: does animation have added value in the restorative effect of natural stimuli?
So far I’ve tested the stimuli in sets containing 6 or 12 slides. The sound didn’t have a direct relation to the images. In this experiment I want to take the stimulus a step further.
I’ve been working on a program to produce randomised computer generated landscapes which consists of hills with shrubs and water. On top of that different animated elements are projected: clouds, flocks of birds, bees, butterflies, blossom leaves and waves on the water.
All the elements move at their own speed and behave in an appropriate manner. By pressing certain keys I can make the elements appear and disappear from the screen. That way I constructed a scenario which I recorded on video. The stimulus isn’t responding to the heart-rate yet because I want to gain insight into the effects of animation. This way I’m sure the whole group gets the same input. Sound artist Julien Mier continued to work on the sounds and made a score to match the images and direction of movement on the screen.


Due to lack of participants I had to reduce my conditions from 4 to 2, focussing on my own animation instead of also testing photo realistic versions. I worked with two groups: one group viewed the full video with accompanying sound. The other group got the full soundtrack but viewed only a still from the animation. That way I can test for the possible added effects of the animation element.

Subjective tension

The variables to be tested (the dependant variables) are:
Subjective feeling of tenseness. Participants score on the statement: “I feel tense.” This is measured on a 7 point likert scale going from not at all to the most tense ever. Beats per minute, inter beat interval (calculated from BPM), heart-coherence, heart-rate variability and Galvanic skin response. To measure the latter I used a separate device, the Mindtuner, which Malcolm from Heartlive kindly lend me. Two electrodes are placed around two fingers. A drawback is that the data is output in a separate file so I will have to do some data cleaning later to match the data with the events. But it will be nice to see how the skin conductivity behaves as this is a good indicator of stress.


The experiment starts with the measurement for subjective tenseness. This is followed by a 5 minute baseline measurement where people are asked to relax while looking at a black screen. After reading instructions participants engage in a cognitive stress task. They have to do subtractions within a limited time span. The more correct answers they give the shorter the time they have to do the calculations. There are 27 calculations in the task. Depending on the speed of the participants this task takes around 2 minutes. They then have to fill in the subjective tenseness questionnaire again. Then they watch either the five minute animation with sound or the still with sound. The experiment finishes after they have filled in the tension questionnaire.


The lab is located in a separate room at the BKKC office. Participants are seated at a table at 200 cm from a TV screen. The image shown is 84,5 x 61,5 cm. The sound was play using an active noise cancellation headphone (Bose Quiet Comfort 25). We choose these headphones because the building is located close to railway and a lot of office noises penetrate into the lab.

Many thanks go to BKKC for their support with the promotion and organisation of the experiment. Special thanks go to Hans and Laetitia. Without their help this experiment would have been impossible.

Virtual View: conducting the first experiment

Now that the research goal is clear, the stimuli are collected and the methods are clear and integrated in the EventIDE experiment it was time to look for participants. We needed at least 30 participants equally divided between men and women. Avans Hogeschool  has thousands of students and staff so we didn’t expect that to be a problem. The students wrote an inviting message on a digital notice board asking people to participate but only got two reactions. Enter the next strategy: walking up to anyone they met and just ask them to take part. That worked a lot better and most of the participants were recruited in this way. Some of the classmates were invited through text messages as well. In the end 33 participants took part, a mixture of students and staff.

Photo by Carlos Ramos Rodriguez

The students arranged the lab set-up and together we determined the protocol. The lab was a small classroom with a smart board with speakers. The students cleared most of the room, leaving it clutter free. The table was installed at a distance of 250 cm from the smart board. The projection was 154 x 108 cm. For the record I checked the sound levels of the different sets in the lab set-up with my decibel meter. They might have a strong influence so it is good to know at what average levels the sounds were played.

The sound level during the baseline measurement (no sounds were played) was 33 decibel. The autumn set with repetitive bird sounds 47 decibel, deflecting vistas with birds and running water sounds 43 decibel, hospital interiors with hospital waiting room sounds 48 decibel, standard preferred landscape with running water sounds 48 decibel and abstract landscape paintings with melodious bird songs 56 decibel.

Sketchup made by students Avans

The students lead the experiment, I came for the first couple of trials to taste the atmosphere and give some tips. At arrival people were welcomed and asked to turn off their phones. We also asked if they’d been to the bathroom. Because we use quite a lot of running water sounds and the experiment lasts around 20 minutes this might become an issue for people. We didn’t want them to get distracted because they needed to go to the bathroom and couldn’t. The sensor was placed on the earlobe. Participants were explained the course of the experiment and told that all data was anonymous and that they could leave at any time should they feel the need to end the experiment.

Participant id, age and gender were entered by the experiment leaders and then the participants were left alone with the stimuli and the questions.

As soon as the experiment was over the leaders would enter the lab for removal of the sensor and debriefing. Most participants were enthusiastic about the experiment and agreed to take part in the next experiment.

The next step is analysing the data, I can’t wait for the results!