Circadian lighting,
honestly assessed
There is good research behind tunable lighting and a great deal of marketing on top of it. The two are worth separating before anyone pays for it.
The underlying idea is not controversial: light intensity and spectrum change across a natural day, human physiology responds to that pattern, and interior lighting that holds one fixed value all day does not reproduce it. Tunable systems let a room follow a curve instead of sitting on a single point.
What it can reasonably be expected to do
- Make a room usable at different hours without the lighting feeling wrong at any of them.
- Reduce the jarring quality of bright, cool light late in the evening.
- Render color more accurately — skin, timber, textiles, paint, and artwork — than a fixed lamp of the same brightness.
- Remove the need for anyone to think about it, once a schedule is set.
What it is not
It is not a treatment. Lighting is not a clinical intervention for a sleep disorder or a mood disorder, and any claim in that direction should be read as marketing rather than as medicine. Anyone with a genuine sleep problem should be talking to a clinician, not to a lighting supplier.
A useful test of a supplier: ask what the lighting will not do. If the answer is that there is no downside, you are being sold to.
Where the premium is justified
Tunable, high color-rendering light earns its cost where color accuracy genuinely matters and where the room is used across the whole day. A room with art in it. A kitchen that is a workspace in the morning and a dining room at night. A primary bedroom. It is much harder to justify in a corridor, a utility room, or anywhere the light is either on or off and nobody looks at anything closely.
Questions worth asking before you commit
- Which specific rooms benefit, and which are being included because it was simpler to specify the whole apartment?
- What happens to the schedule when someone works nights, or travels?
- Who adjusts the curve after handover, and is that a service call?
- If the fixtures were fixed color temperature instead, what exactly would be lost in this room?
The honest position is that tunable lighting is a real improvement, unevenly distributed. Specify it where it does something. Do not specify it everywhere because it is available.