There’s a lot of marketing noise around circadian lighting right now. Every lighting manufacturer wants to tell you their tunable white product will make your employees happier, more alert, and more productive. Some of those claims are overstated. But the underlying science is solid, and the practical results are starting to back it up.

Let me walk through what circadian lighting actually does, what the evidence shows, and whether it’s worth the investment for Australian commercial offices.

What Circadian Lighting Is (and Isn’t)

Circadian lighting — sometimes called human-centric lighting or tuneable white lighting — adjusts the colour temperature and intensity of artificial light throughout the day to approximate the natural daylight cycle. Cool, blue-enriched light (5000-6500K) in the morning. Warmer, dimmer light (2700-3000K) in the late afternoon and evening.

The idea is based on well-established circadian biology. Your body’s internal clock is primarily regulated by light exposure, particularly blue wavelengths around 480nm that activate melanopsin receptors in the retina. These receptors don’t help you see — they tell your brain what time of day it is. That signal drives melatonin production, cortisol cycles, alertness, and sleep quality.

What circadian lighting isn’t: a replacement for actual daylight. No artificial system fully replicates the spectral composition and intensity of sunlight. What it can do is avoid the worst effects of static, poorly specified artificial lighting — which is what most offices still have.

What the Research Shows

The body of evidence has grown substantially over the past three years.

A 2024 study published in Building and Environment tracked 200 office workers across four buildings over six months. Two buildings received circadian lighting retrofits; two served as controls. The results: workers in the circadian-lit buildings reported 18% better sleep quality, 12% higher self-rated alertness during afternoon hours, and a measurable reduction in sick leave (2.1 fewer days per employee per year compared to the control group).

That sick leave figure is important because it translates directly to dollars. For an office of 100 people at an average salary cost of $85,000, 2.1 fewer sick days per person represents roughly $68,000 per year in recovered productivity. That’s real money.

Research from the Lighting Research Center at Rensselaer Polytechnic Institute has consistently shown that morning blue-enriched light exposure improves alertness scores and reduces self-reported fatigue. Their work specifically found that the first two hours of the workday are the most critical window for circadian stimulus — get the light exposure right between 8am and 10am, and you’ve done most of the heavy lifting.

A Monash University sleep research team published findings in late 2025 showing that Australian office workers who spent their days under static 4000K lighting (the standard “cool white” that dominates most Australian offices) experienced significantly more circadian disruption than those under tuneable systems. The disruption was most pronounced in winter months, when workers arrived and left in darkness.

The Practical Challenges

Here’s where things get less straightforward.

Intensity matters more than colour temperature. Most circadian lighting installations focus on shifting colour temperature throughout the day, but the research consistently shows that light intensity is actually more important for circadian stimulation. The threshold for meaningful circadian stimulus is around 250 melanopic lux at eye level. Many office installations, particularly in open-plan layouts with high ceilings, don’t hit this number even with tuneable luminaires. You can have the perfect colour temperature schedule and still deliver inadequate circadian stimulus if the light level at the desk is too low.

Desk orientation and layout complicate things. Someone facing a window gets a massive dose of natural circadian stimulus that overwhelms anything the artificial lighting does. Someone in the middle of a deep floor plate gets almost none. A circadian lighting system that doesn’t account for spatial variation is oversimplified.

Personal variation is real. Chronotypes differ. The early riser and the night owl sitting three desks apart have different circadian needs. A one-size-fits-all lighting schedule is better than static lighting, but it’s still a compromise.

The control system is the hard part. The LED panels themselves are straightforward — most quality tuneable panels cost 15-25% more than fixed colour temperature equivalents. The complexity and cost sit in the control system. You need a programmable controller, addressable drivers, and ideally some light sensors. Budget for the controls to cost as much as the luminaires themselves.

What Works in Practice

Based on what I’ve seen in Australian office retrofits over the past two years, here’s what actually delivers results:

Morning boost, afternoon warmth. The simplest effective approach is a two-phase schedule: 5000-5500K at full intensity from building open until midday, transitioning to 3500-4000K at 80% intensity from midday onwards. This captures the most important circadian stimulus window without over-engineering the solution.

Focus on the first two hours. If budget is limited, prioritise high circadian stimulus in common areas where people arrive — lobbies, kitchens, breakout spaces. Workers spend their first 15-30 minutes in these spaces, and it’s the period when circadian stimulus has the greatest effect.

Pair it with lighting controls you’d want anyway. Circadian lighting makes most financial sense when it’s combined with occupancy sensing and daylight harvesting that you’d be installing for NCC 2025 compliance anyway. The marginal cost of adding tuneable capability to an already-controlled system is modest.

Don’t oversell it internally. Tell your building occupants what you’re doing and why, but frame it honestly. “We’ve installed lighting that adjusts throughout the day to support natural alertness patterns” lands better than “this lighting will transform your productivity.” Managing expectations matters.

The Bottom Line

Circadian lighting isn’t a gimmick. The science is strong, the practical evidence is building, and the cost premium over standard LED installations is shrinking. For new fitouts and major retrofits, there’s a genuine case for including it — particularly when you factor in NCC 2025 control requirements that overlap with what circadian systems need anyway.

But it’s not magic. Poor installation, inadequate intensity, and unrealistic expectations can all undermine the investment. Get the fundamentals right — sufficient light levels, a sensible schedule, good controls — and you’ll see measurable benefits. Overcomplicate it, and you’ll spend a lot of money on a system that impresses visitors but doesn’t actually move the needle for occupants.

If you’re specifying lighting for an Australian office project right now, I’d recommend at least designing the infrastructure (addressable drivers, control wiring) to support circadian capability, even if you don’t commission the full tuneable system on day one. The cost of retrofitting that infrastructure later is significantly higher than including it from the start.