Cycles shorter than 24 hours
Ultradian
Cycles of focus, alertness, and energy that govern how people perform across the day — typically running in 90 to 120 minute waves.
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The science
Every environment is giving
the body instructions.
The body doesn’t read your design brief. It reads light, temperature, time cues, and movement. Whether an environment supports or disrupts human biology is not a matter of intent — it’s a matter of what the body is actually being told.
The primary input
65%
of the input that governs
human circadian rhythms.
Light accounts for the majority of the signal the body uses to set its clock. Sleep-wake timing accounts for another 15%. Meals, movement, and social cues make up the remainder.
Yet indoor lighting — even in well-designed spaces — is almost never designed with this in mind. Designers aren’t trained in biology. Architects aren’t trained in chronobiology. The little science that does make it into the brief rarely survives value engineering.
The result is environments that look considered but function against the people who inhabit them.
What the evidence shows
The body isn’t broken.
It’s extraordinarily responsive.
Wright et al. (University of Colorado Boulder, Current Biology, 2017) studied adults exposed to a natural summer light-dark cycle during a weekend camping trip — natural light only, zero electrical lighting, zero electronic devices.
A single weekend of natural light exposure achieved 69% of the circadian phase shift previously documented after a full week.
The implication is not that everyone should live outside. It’s that the body responds quickly — and powerfully — to the right conditions. Built environments can provide those conditions, if they’re designed to.
Beyond circadian
The full rhythm spectrum.
Circadian is the most recognisable — but it is one rhythm among several that environments either support or interrupt.
The 24-hour cycle
Circadian
The master rhythm. Governs sleep-wake timing, hormone release, immune function, cognition, and mood. Light is its primary input.
Cycles longer than 24 hours
Infradian
Weekly, monthly, seasonal cycles — including hormonal and menstrual rhythms. Often ignored in environment design; a significant source of under-acknowledged friction.
From evidence to operation
The research is ready. The question is what you do with it.
Our approach translates evidence into environments, products, and brands that measurably support human biology.