Physiological state determines the quality of thinking

In my last post, I described the “more is more” mechanism. It’s a vicious cycle in which insufficient recovery and declining work performance are compensated for by increasing the workload and resorting to quick dopamine-boosting strategies. Culture rewards the ability to ignore one’s own limits, and many people build their identity on the basis of performance. However, repeatedly ignoring physiological needs alters the state of the nervous system, reduces capacity, and impairs decision-making and quality of life.

No one can reach their full potential when in a state of poor physiological health. Our physical condition has a powerful influence on how we perceive our environment. An overstimulated system is quick to perceive threats and a sense of urgency. A balanced system recognizes more options and opportunities. Physiological balance thus serves as the default setting for the brain’s information processing and forms the foundation for sustained performance.

The brain processes information on three interconnected levels.

The first level is physiological. It refers to the state of the body and nervous system at this very moment. Breathing, heart rate, blood sugar, fluid balance, muscle tension, hormones, and the activity of the autonomic nervous system constantly send information to the brain. This data is processed nonstop without conscious involvement. It is not a matter of thinking but rather the system’s default state.

The second level is implicit information processing. It forms a rapid and automatic system that recognizes patterns, anticipates situations, and produces immediate interpretations. A large portion of everyday decisions are made at this level. The implicit system always operates within a physiological state. The nervous system’s arousal level influences whether a situation is interpreted as urgent and threatening or as neutral.

The third level is analytical information processing. This system operates consciously and more slowly. It enables the comparison of options, long-term thinking, and the regulation of impulses. The analytical system is precise but has limited capacity. Stress, sleep deprivation, and physical strain quickly impair its functioning.

These three levels form a constantly interactive whole. Thoughts can calm the body, and the body’s state can be altered through conscious regulation. However, the effect is not symmetrical. The physiological state affects the mind more quickly and more strongly than the mind affects physiology. The body’s baseline state forms a framework within which implicit and analytical information processing takes place.

Stress acts as a key mechanism that alters this basic physiological state. Stress does not simply mean anxiety or mental pressure. It is the body’s reaction to a disruption in balance. Any deviation from basic needs acts as a stressor. Irregular eating, insufficient exercise, sleep deprivation, non-stop cognitive work, and a constant flood of stimuli increase the body’s overall stress load.

The strain also builds up. Lack of sleep, a sedentary lifestyle, and intense work pressure reinforce each other’s effects. The nervous system becomes more prone to a state of overstimulation, stress hormone levels remain elevated, and recovery slows down.

The nervous system’s arousal level directly affects how we interpret our environment. A stressed system is more likely to recognize risks than opportunities. An overstimulated nervous system interprets even neutral stimuli more readily as threats. A balanced state allows for a broader perspective, more creative problem-solving, and a stronger sense of connection with others.

Without a stable physiological foundation, performance relies on constant internal friction. A body that functions in balance reduces friction and unlocks capacity.

Physiological balance does not mean rigid discipline. Routines serve as a framework for calibration. The basic framework is designed to function on a typical day: sufficient sleep, regular meals, planned exercise, and rest periods. The overall plan is adjusted individually based on experience. Increased workload increases the need for recovery, and increased energy requirements increase the need for nutrition. The framework remains the same; adjustments are made according to the situation.

Without such a structure, everyday life easily becomes a constant series of reactions. Working life already involves a great deal of reactivity. Schedules change, pressure mounts, and decisions must be made constantly. Routines reduce this burden by automating basic management tasks.

This perspective also reveals the performance paradox. Culture often encourages us to add more: more projects, more goals, and more stimuli. From a physiological standpoint, the system often works the opposite way. A slightly lower overall load often increases available capacity. Less constant reactivity and a slightly simpler daily routine stabilize the nervous system’s baseline state.

In this sense, less really can be more.

1. Sleep

Sleep is the nervous system’s most important recovery mechanism. During sleep, activity in the stress response system decreases, metabolic byproducts are cleared from the brain, and cognitive systems recover. Insufficient sleep rapidly impairs attention, working memory, and decision-making. Even after just a few nights of poor sleep, the capacity for analytical thinking begins to decline.

2. Nutrition

The brain consumes a large portion of the body’s energy. Irregular eating habits and sharp fluctuations in blood sugar levels increase the strain on the nervous system and make it harder to concentrate. A steady intake of nutrients helps maintain a more stable physiological state and supports cognitive performance.

3. Movement

Movement is one of the key ways to influence the body’s physiological baseline and the nervous system’s state of arousal. Through movement, the body can be shifted from a state of stress toward a state of balance.

Inactivity is not a neutral state for humans. Human physiology is designed for regular movement. Long periods of sitting still impair blood circulation, restrict chest movement, and increase muscle tension, particularly in the neck and shoulder area. At the same time, breathing often becomes shallower and the load on the autonomic nervous system increases. If prolonged, this state begins to increase physiological stress.

Movement breaks this vicious cycle. Even relatively short periods of movement restore blood circulation, loosen up the tissues, and make breathing easier.

The human nervous system also reacts strongly to changes. A clear transition from exertion to recovery facilitates the regulation of the system.

Intense strength training often acts as such a regulatory mechanism. A heavy workload activates the nervous system, but once the workout ends, the body shifts toward recovery. For many people, the contrast between the exertion and the subsequent relaxation makes it easier to transition into a calmer state.

Strength training also affects body alignment and tissue function. The function of the tissues in the front of the chest, the hip flexors, and the muscles of the neck and shoulder region influences how the chest moves and how breathing occurs. More balanced muscle function allows for freer movement of the chest and deeper breathing, which supports the nervous system’s transition toward a calmer state.

Light aerobic exercise affects nervous system regulation through a slightly different mechanism. Walking, cycling, and other low-intensity activities lower blood pressure, improve blood circulation, and increase oxygen delivery to tissues. At the same time, the autonomic nervous system often shifts toward parasympathetic activity, which supports recovery and balances the body’s stress response.

Exercise, then, doesn't just affect your muscles and fitness. It also acts as a regulator of the nervous system.

The physiological state as the basis of thought

Our physiological state serves as the default setting for the brain’s information processing. It influences how the implicit system interprets situations and the capacity at which analytical thinking operates. Our experience of the world is constructed through this biological information processing.

The nervous system quickly adapts to certain baseline states. Prolonged stress begins to feel normal, even though it narrows our thinking and our perception of the world around us. Change often only becomes apparent when we start to shift that baseline in a different direction. After a good night’s sleep, regular meals, or exercise, thinking becomes clearer and perspective broadens. This shows just how strongly the body’s state influences how we interpret our surroundings, make decisions, and perceive the world.

Kasper Kortelainen, Peak Performance Coach at Epitome