The somnologist explained the influence of standard schedules on the lives of larks and owls

Some people get up at six in the morning and manage to redo half of their tasks by noon. Others, at the same time, can barely focus their eyes and begin to think normally in the late afternoon. Society has long made a verdict: the former are disciplined and successful, the latter are lazy and weak—willed. But science does not agree with this. How the chronotype affects life, whether it can be changed and why people with the owl chronotype cannot be called lazy — in the Izvestia article.

What is a chronotype and why is it different for everyone?

A chronotype is a biologically determined tendency of a person to fall asleep and wake up at a certain time of the day. Not just a habit or a weakness of will, but a stable characteristic fixed at the level of neurobiology. Larks wake up early, are most active in the morning and feel tired in the evening. Owls, on the other hand, have difficulty functioning in the morning, but they get into a working rhythm closer to night — and this is not a whim, but a physiology.

At the heart of everything are circadian rhythms — biological cycles about 24 hours long that regulate almost all processes in the body: body temperature, hormone production, blood pressure, immune response and, of course, sleep. The main conductor of this system is the suprachiasmatic nucleus of the hypothalamus, or a tiny structure in the brain that receives signals from retinal cells about the amount of light and, depending on this, commands the production of melatonin. When it gets dark, melatonin rises, and the person feels sleepy. But in larks, this process starts at about 18:00, whereas in owls — no earlier than 22:00-23:00 and often later.

In an interview with Izvestia, the specialist emphasized that the chronotype is significantly related to genetics, but this is not a verdict. According to him, this is also influenced by age, the amount of light in the morning and evening, work schedule, social habits and physical activity level. Buzunov also noted that if it is difficult for a person to get up at 06:00 and work comfortably in the evening, this is not always "promiscuity". In many cases, as he noted, this is a real biological feature.

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At the same time, the chronotype is not a constant for life. People tend to be early risers in the first 10 years of life, then shift towards owls in adolescence. By the age of 60, the regime returns to what it was like in childhood. This shift in adolescence is due to hormonal changes: during puberty, the biological clock is physiologically adjusted to a later mode. A study by a group of scientists from Argentina, published on the arXiv, showed that in adolescents, the chronotype reaches its maximum "lateness" between the ages of 18 and 24, and only after that it begins to shift back to an earlier mode.

A recent study by McGill University and the Mila Institute of Artificial Intelligence, published in Nature Human Behavior, went even further: scientists analyzed data from 27,030 participants from the UK Biobank and found that the chronotype is associated with specific brain structures. The chronotype is particularly closely related to the basal ganglia, limbic system, and cerebellum, structures responsible for reward processing, emotion regulation, and behavioral patterns. In other words, the time at which a person feels comfortable falling asleep and waking up reflects the underlying neurobiological features of his brain.

A world built according to the larks' schedule

Most people don't think about why the working day starts at eight or nine in the morning instead of noon. It seems natural, but it is a historically and culturally determined choice. Pre-industrial societies lived by the sun: they got up at dawn and went to bed at sunset. Agricultural labor required an early start—crops, livestock, markets. The Industrial Revolution consolidated this rhythm in the form of work shifts and fixed schedules. Schools, offices, and government agencies have all adjusted to the same standard.

With it came the moral burden. "Whoever gets up early, God gives it to him" — this proverb exists in dozens of languages. Benjamin Franklin wrote: "Going to bed early and getting up early makes a person healthy, rich and wise." Victorian England turned early rising into a virtue, and late awakening into a vice. In the 21st century, biohackers, CEOs, and influencers have been added to this, competing to see who gets up earlier: five in the morning, four, three. Getting up early has become a marker of productivity and success.

But there is a simple logistics behind this romanticization: the world really works according to the schedule of the early chronotypes. The one whose biological peak falls in the morning lives in sync with the environment. Whoever it is for the evening has to imitate a lark every working day. This creates not just discomfort, but a real physiological burden.

The advantages of larks — and the price that owls pay

There is indeed evidence that an early chronotype correlates with better health and well—being, and there are many of them. A study published in Nature Communications found that rising early is associated with higher levels of well-being, while owls have an increased risk of psychiatric disorders, including schizophrenia and depression. Larks, on average, show a more stable sleep pattern, better physical health indicators, and a lower risk of cardiovascular disease.

A University of Birmingham study published in BMJ Open Sport & Exercise Medicine tested the cognitive and physical performance of 56 healthy people with different chronotypes throughout the day. Larks performed best in cognitive tests at 8:00 a.m. and outperformed owls by 7-8% at that time. Night owls were significantly more sleepy in the morning: their reaction time was 8.4% slower and their physical strength was 7.4% lower compared to larks.

However, the key issue here is the causal relationship. Larks are healthier not because they get up early on their own. They are healthier because they live in accordance with their chronotype: their biological clock coincides with the schedule that society sets. Owls find themselves in a fundamentally different situation.

When a person with a late chronotype gets up a few hours earlier every weekday than his biology requires and makes up for sleep on the weekend, a phenomenon called social jet lag occurs.

The scale of the phenomenon is impressive. According to research, about 50% of people suffer from social jet lag to one degree or another. Its effects go far beyond morning fatigue. Preliminary results of a study presented at the American Academy of Sleep Medicine conference and published on ScienceDaily showed that every additional hour of social jet lag increases the risk of cardiovascular disease by 11%. At the same time, the effect persists regardless of the total duration of sleep and the presence of symptoms of insomnia.

Other documented effects of social jetlag include mood deterioration, cognitive decline, increased anxiety, problems with the intestinal microbiome, and weight gain. The greater the gap between a person's biological schedule and their actual regime, the more serious the consequences. Moreover, owls suffer from this discrepancy incomparably more than larks, simply because their biological clocks initially diverge from social norms.

Somnologist Buzunov emphasized that the social jet lag can be partially compensated. According to him, a person with this type of jet lag chronically lacks sleep on weekdays, but on weekends, on the contrary, gets enough sleep. He clarified that the main problem is that the body experiences an artificial "jet lag" every week. It's like constant long-distance flights.

The expert stressed that it is better not to compensate for the social jet lag, but to minimize it by making the regime as stable as possible and reducing the conflict between biology and the schedule of life. Buzunov recommends reducing the difference in working hours between weekdays and weekends (no more than two hours), fixing the wake-up time, getting bright light in the morning, reducing the light load in the evening, and, if possible, shifting the work schedule closer to your chronotype.

Is it possible to rebuild the biological clock — and is it worth it

The question that most owls ask themselves is: is it possible to change the chronotype? The answer is ambiguous. Partially— yes, within certain limits. At the same time, Buzunov emphasizes that the chronic discrepancy between the biological clock and the social schedule is indeed associated with health risks.

According to the somnologist, over time, increased daytime sleepiness, decreased concentration, irritability, as well as a higher risk of anxiety and depression may occur. In addition, over the years, a person may experience metabolic disorders, weight gain, and an increased risk of cardiovascular disease.

It is important to understand that forced early awakening without shifting the phase of falling asleep does not rebuild the chronotype — it creates a chronic sleep deficit. Owls show a greater variability of indicators throughout the day, which suggests their higher sensitivity to changes in the time of day. This means that an owl who works according to the lark's schedule suffers more than a lark who sometimes has to work late.

Chronic lack of sleep is one of the most destructive factors for health. It disrupts glucose metabolism, increases cortisol levels, weakens the immune system, impairs memory consolidation, and increases the risk of depression. Moreover, the key word is "chronic": the body tolerates one-time lack of sleep without serious consequences, but systemic lack of sleep for an hour and a half every day accumulates in debt, which the body exposes in the form of diseases.

What should an owl do in the world of larks? Several strategies work better than others. The first is to recognize your chronotype as a biological given and stop considering it a personal disadvantage. The second is to look for flexibility where it exists: remote work, flexible working, negotiations with the employer on a rolling schedule. The third is to synchronize the most demanding tasks with the personal peak of activity: if productivity begins at 19:00, it is at this time that complex negotiations and creative work should be planned. The fourth is to eliminate the social jet lag as much as possible: do not try to sleep off the weekend due to a catastrophically late rise, but keep the gap between the weekday and non—working schedule for no more than an hour.

At the same time, the specialist stressed that it is important not to "break" biology. According to him, if the innate owl is rigidly forced to live according to the lark's schedule, chronic desynchronosis often occurs — a state of constant lack of sleep and fatigue. Therefore, the task is usually not to "completely remake oneself," but to find the most sustainable and realistic compromise between biology and the demands of life.

McGill scientists explicitly point out that understanding the neurobiological foundations of the chronotype is important not only for science, but also for practice. It can form the basis of personalized interventions, from regimen recommendations to targeted treatment of mood disorders based on circadian factors.

Until that happens, the most honest answer is that the biological clock is neither an enemy nor an ally. It's just a device that ticks differently for different people. The problem is not that owls can't get up early. The problem is that the world has not yet learned to take this into account.