Make better lighting decisions based on data
Lighting can meet every standard and still leave people short of the light they need. LYS measures the light they actually get.
From lighting targets to personal light exposure
In 2022, leading circadian scientists recommended at least 250 lux melanopic EDI (mEDI) during the day. But personal light exposure varies as people move through spaces and follow different routines. LYS adds this human dimension to lighting analysis, helping designers understand how the light people actually receive compares with science-based recommendations.¹
Same building. Same day. Different light
We put LYS Buttons on people spending one conference day in the same building. The five who got the most light received ten times the melanopic dose of the five who got the least. Where people sit, when they take a break and whether they step outside all change the light their body clocks receive.
Each line and bar is the average of five people, counting only the time the Button was worn; no individual's data is shown.
Better buildings start with understanding personal light.
As healthier buildings and human wellbeing gain importance, personal light exposure adds a valuable new dimension to lighting design. The same space can deliver different light doses depending on people's routines, movements and individual biological rhythms.
Together with existing daylight and lighting analysis, these insights help advance healthier, more human-centric and sustainable buildings.
What LYS shows
Measured on the people in the space, not at a fixed point in the room.
How much light people actually get as they move through a building.
Between rooms, floors, desks and times of day.
Whether a design works after people move in.
Where you can use it
Three ways architects, lighting designers and building owners use LYS.
Check that the daylight and electric light a design promises reaches the people who will use it.
Measure how a space performs for its occupants after they move in, not only on the drawings.
Compare rooms, floors and times of day against science-based recommendations to see where light falls short.
Measured in real buildings
Published research has used LYS Buttons to compare the light people get in offices, at home and on hospital wards.
The Relationship of Light Exposure to Sleep Outcomes Among Office Workers, Part 1: Working in the Office vs. at Home Pre/Post COVID-19
Compared everyday light exposure and sleep outcomes when office workers worked in the office versus at home, recording personal exposure with a LYS Button.
Read the study →The Relationship of Light Exposure to Sleep Outcomes Among Office Workers, Part 2: Comparison of Days With and Without Social Constraints
Examined how everyday light exposure relates to sleep on days with and without work-related social constraints, recording exposure every 15 seconds with a wearable LYS light detector.
Read the study →Evaluating Occupant Light Exposure and Usage Patterns in an Inpatient Behavioral Health Unit
Investigated staff light-exposure patterns in an inpatient behavioural-health setting using wearable and stationary LYS sensors.
Read the study →In care homes, the light residents actually received differed significantly from room-level measurements. Jao et al., Innovation in Aging, 2025 →
How a project runs
From the first question to findings you can share, in four steps.
- 01
Scope
We define the question with you.
- 02
Measure
People wear LYS Buttons during normal working days.
- 03
Compare
We compare spaces and times against the expert targets.
- 04
Act
You get findings to act on and share with your client.
Button V1 for building projects
Light and movement on the people in the space, with melanopic EDI, at a price that lets you equip a whole floor. Teams running their own project can order Buttons directly.
Button V1, USB-C charging dock, USB-C cable
Typically within 7 working days
No subscription
12 months
From 5 units, PO accepted
Need spectral channels or flicker detection? Compare V1 and PRO.
Light data with activity context
Everyday light data with movement context, in a compact, unobtrusive design.
- Light data
- Red, green, blue and near-infrared (RGB + NIR).
- Movement sensing
- A 3-axis accelerometer adds activity context to light measurements.
- Compact and unobtrusive
- A compact, unobtrusive design for everyday wear.
Specs, best for and apps
- Battery life
- 5 days
- Sampling interval
- Every 15 seconds; custom intervals by arrangement
- On-device storage
- At least 24 hours at the default interval
- Syncing
- Once a day at the default interval
LYS Collect: research data collection, no feedback to participants (iOS and Android)
LYS Data Portal: manage participants, monitor collection and export data
Questions designers and building owners ask
What a LYS project measures, and what you get from it.
Why measure light on people instead of in the room?
A light meter measures one fixed point. People move between desks, meeting rooms, corridors and outdoors, so two people under the same lighting plan can end the day with very different light doses. LYS measures the light that actually reaches each person.
What target should a space meet?
The 2022 expert consensus recommends at least 250 mEDI lux at eye level during the day. LYS shows how the light people actually receive compares with it.
How does a LYS building project run?
In four steps: we scope the question with you, people wear LYS Buttons during normal working days, we compare spaces and times against science-based recommendations, and you get findings to act on and share with your client.
Can LYS test a design before and after a change?
Yes. Measure before a change and again after, or compare two spaces side by side, with the same people where possible.
Show your clients how your light performs for people
Talk to us about a project, or order Buttons for your team.
- ¹ Expert consensus: Brown et al., PLOS Biology, 2022. pubmed.ncbi.nlm.nih.gov/35298459