DEFINING CHRONOTYPES WITH BIOSIGNALS - A LOOK INTO DATA
Hannu Kinnunen
Hannu Kinnunen is the brains behind the science that makes ŌURA the most advanced wearable vital signs monitor in the world. With a long career at heart rate monitor maker Polar, Hannu was responsible for the physiological algorithms, many of which are still used in Polar products today. Hannu is credited in dozens of patents and scientific articles on the field of heart rate based signal processing, biosignal detection, and the analysis of activity, training, recovery and sleep.
Hannu Kinnunen discusses defining individual chronotypes and circadian alignment using bios
The real challenge is to organize our life so that we improve the quality of our life, our health and performance in the long term.
Summary
- Chronotypes are genetically and biologically determined, ranging from morning to evening types, and can only be adjusted slightly through lifestyle choices. - Modern society disproportionately favors morning types, causing "social jet lag" for evening types, which correlates with lower academic performance and higher health risks. - Every bodily function, including hormone production and cognitive alertness, has an optimal time within the 24-hour cycle controlled by internal biological clocks. - Using biosignals like heart rate variability and temperature allows individuals to identify their circadian alignment and make data-driven changes to improve sleep quality. - Long-term health and performance depend more on consistent circadian rhythms and life organization than on meeting daily activity targets like step counts or calories.
Article
Defining Chronotypes With Biosignals And Data
A Look Into Circadian Alignment At Biohacker Summit 2017 Helsinki
At Biohacker Summit 2017 Helsinki, held in Helsinki, Finland, on 13 October 2017, Hannu Kinnunen delivered a presentation that cut through the noise of modern self-optimization and landed on a more intimate question: not how much we do, but when our bodies are ready to do it.
Kinnunen, the scientific force behind ŌURA’s biosignal-driven wearable technology and a veteran of physiological algorithm development at Polar, used his talk, *Defining Chronotypes With Biosignals - A Look Into Data*, to argue that the rhythms governing human performance are neither motivational slogans nor lifestyle fashions. They are biological facts, written partly in our genes and revealed, increasingly, through data.
“Every function in our body has its optimum time in the twenty-four-hour cycle,” he said.
The Clock Beneath Consciousness
The central premise of Kinnunen’s talk was deceptively simple: the body keeps time with extraordinary precision. Beneath waking decisions and social obligations sits a layered timing system, from cellular clocks to the brain’s master clock, orchestrating everything from hormone release and digestion to alertness, recovery and sleep pressure.
Chronotype, in this framework, is not a personality quirk. It is a biological orientation. Morning types and evening types are not merely disciplined or lazy, productive or indulgent. They are living on different internal schedules.
“Our chronotype is determined by our genes; it is biological, and we can only adjust it slightly,” Kinnunen said.
That point mattered because modern life still treated time as universal when physiology did not. Office schedules, school start times and social expectations tended to reward those whose bodies naturally rose early. For those whose clocks ran later, the result was often a chronic collision between biology and obligation.
The Quiet Violence Of Social Jet Lag
Kinnunen pointed to data linking so-called social jet lag with poorer academic outcomes, especially among young people. The term describes the gap between a person’s natural sleep timing and the schedule imposed by work or school. In practice, it meant waking early on weekdays, then sleeping later on weekends to recover what had been lost.
The pattern was more than inconvenience. In the research cited during the presentation, greater social jet lag correlated with lower grade point averages and higher dropout risk. Evening types, in other words, were not merely inconvenienced by a morning-biased society. They were structurally disadvantaged by it.
This was one of the talk’s sharpest insights: health and performance were being shaped not only by individual habits but by a social architecture that ignored biological diversity.
What Biosignals Could See That Schedules Could Not
Where older debates about sleep often relied on questionnaires and self-reporting, Kinnunen showed how biosignals offered a more continuous and revealing portrait of circadian life. Through measurements such as heart rate variability, resting heart rate, temperature and long-term sleep timing, the ŌURA ring was presented as a tool for mapping the body’s alignment, or misalignment, with its own internal clock.
The real promise, in his telling, was not surveillance for its own sake. It was interpretation. Data could expose the small conflicts people had come to normalize: late screen exposure, irregular weekends, family routines that shifted sleep windows, meals and activity that landed out of sync with recovery.
“Everything you do, from your daily activities to what and when you eat, affects how you sleep, your recovery, and your hormonal balance,” he said.
That chain of cause and effect was central to the argument. Sleep was not an isolated event at the end of the day. It was the downstream result of dozens of earlier decisions.
Two Bodies, Two Different Days
One of the most compelling sections of the presentation came as Kinnunen walked through long-term data from individual users, contrasting morning and evening chronotypes not as abstract categories but as visible patterns.
A morning-type subject showed sleep timing closely aligned with sunrise and sunset across the seasons, with bedtimes clustered around 9pm and wake times near 6am. Activity, too, remained largely inside daylight hours. The data formed a picture of unusual coherence: a life largely synchronized with environmental light.
An evening-type subject, by contrast, showed later bedtimes, weekend sleep-ins and a more pronounced struggle with seasonal light variation. The user’s activity began later, and sleep patterns bent noticeably under the pressure of weekday demands and family obligations. Weekend oversleeping told its own story, one of debt rather than leisure.
These examples made visible a truth many people experienced but rarely quantified: the body keeps score when social time and biological time drift apart.
Blue Light, Domestic Life And The Fragility Of Sleep
Kinnunen was careful not to present circadian optimization as an austere fantasy in which everyone simply obeyed a perfect schedule. The lived reality, he suggested, was messier. Work, children, travel and relationships all pulled against ideal timing.
He described cases where people clearly lived in conflict with their chronotype, including parents who delayed sleep because evening was the only quiet interval available to them, and professionals whose schedules repeatedly overrode what their physiology seemed to prefer.
Still, some environmental interventions appeared to matter. In one example, evening use of blue light blocking glasses was associated with improved deep sleep and reduced nighttime disturbance. Kinnunen did not cast this as a miracle cure, but as a reminder that artificial light, especially late at night, remained one of the clearest ways modern living disrupted ancient timing systems.
The body, his data suggested, did not simply surrender to social habit. It resisted, adapted imperfectly and often paid a price.
Beyond Step Counts And Daily Targets
Running through the presentation was a quiet critique of wearable culture itself. Kinnunen did not dismiss tracking devices, but he questioned the shallow metrics that often dominated them: steps, calories, minutes of intensity, the daily target gamified into moral obligation.
“It is much more important to plan your daily rhythms so your life quality and health are ensured than it is to reach your target every single day,” he said.
That sentence reframed the purpose of biosignal technology. The goal was not to win each day on paper. It was to shape weeks, months and years around rhythms that the body could sustain.
This was a more mature vision of health technology, less obsessed with relentless output and more interested in recovery, timing and readiness. The body was not a machine to be pushed to quota. It was an organism whose capacities rose and fell in patterns that could be learned, respected and used.
The Question To Ask Each Morning
If the talk had a philosophical center, it came in the form of a morning question. Kinnunen said the aim was to help people wake up and ask: “What is my body ready for today? What did I do right yesterday, and what did I do wrong?”
“We want people to ask in the morning: What is my body ready for today? What did I do right yesterday, and what did I do wrong?” he said.
That question captured the spirit of the presentation more clearly than any product demonstration could. It was an appeal for feedback over force, for reflection over rigid optimization. Data, in this sense, was not there to shame the user but to help them negotiate with reality, making small, informed adjustments where total control was impossible.
A More Humane Model Of Performance
What Hannu Kinnunen offered at Biohacker Summit 2017 Helsinki was not just a case for biosignal tracking. It was a case for biological humility. Chronotype could not be bullied into compliance. Sleep could not be repaired by willpower alone. Performance was inseparable from timing, and timing was inseparable from the body’s own inherited design.
In a culture that often confused discipline with health, his message landed with unusual clarity: the smartest life was not necessarily the most intense one, but the one best aligned with the clock within.
And in that alignment, measured quietly through temperature, heartbeats and the shape of a night’s rest, lay the possibility of better recovery, sharper performance and a more livable relationship with time itself.
Part of Biohacker Summit 2017 Helsinki