🧠 Core Proposition of the Theory of Sleep Instinct
The entire theory begins with the animal instinct of infants.
At the moment of birth, humans have not yet been conditioned by language, culture, systems, or doctrines, this is the state closest to the instinct of the species. Any theory that attempts to understand fundamental human behavior is almost untenable if it does not begin with the physiology and movements of infants.
And “sleep”—a behavior that spans nearly the entire life cycle, if it is truly instinctive, should reveal its most primitive and undisturbed evidence in infants.
Based on the two premises of "Anti-Artificial Intervention" and "Infant Instinctive Selection," infants are naturally well-suited for prone sleeping.
The so-called "supine position" is not a natural outcome, but an artificial design imposed by modern caregivers driven by safety anxiety, visual management, and liability avoidance. This design stems not from evolution, but from institutional systems.
In contrast, prone sleeping requires no instruction or training, infants naturally assume the face-down posture. This behavior has several key features:
- Performed autonomously, without external prompts;
- Posturally stable, creating surface contact pressure with the bed;
- Hands, feet, and torso in contact with the ground, closely resembling the “cling–press–grasp” reflexes of primate infants.
This is not a random phenomenon, but a continuation of the inherited structure of animal instinct present in infants.
More importantly, we can reference a comparison: most infants under six months of age exhibit the "diving reflex", when the face contacts liquid or specific pressure, the airway automatically closes and the body enters a state of respiratory calming. This indicates:
The infant's body is already equipped with primitive 'animal instinct' behaviors; it can be inferred that “sleeping prone” is an instinctive choice of the infant.
This natural mechanism of interacting with the environment requires no language, no instructions, it is the purest design of biological evolution.
From the natural prone sleeping posture of infants, we can logically infer that adults are also suited to sleep in the prone position.
The logic here is not that “we can imitate infants,” but that “instinctive reactions and animal behaviors present since infancy can persist into adulthood, and should be the point of return for every individual.”
In fact, it’s not just that prone sleeping is suitable, it is the sleeping posture more aligned with human evolutionary logic. For a long time, we have been forced to accept supine sleeping and a series of sleep aids designed around it; in reality, these have distorted the animal instinctive behaviors within us and violated evolutionary principles.
The prone sleeping position naturally generates thoracic pressure, which in turn triggers a series of instinctive physiological responses:
- Pressure restricts thoracic (chest) breathing →
- Shifts to diaphragmatic (abdominal) breathing →
- Rhythmic diaphragmatic breathing →
- Parasympathetic activation →
The chest cannot expand significantly, so breathing can no longer rely on chest movement;
The center of breathing moves downward, led by the diaphragm, entering a slower-paced, more stable airflow pattern;
Through deep muscular rhythm, it stimulates the parasympathetic nervous system;
Guides the entire nervous system into a stable, low-alert, non-fight-or-flight state, triggering processes such as relaxation, repair, and sleep.
This entire sequence requires no “technical training,” no mental preparation, and no breathing exercises, because this is not about “control,” but about “restoration”—restoring an automatic mechanism we already possess.
This corresponds to the two core models of this theory:
1. Signal Decoding Model
Insomnia is not a bodily malfunction, it is the result of the body not receiving the “ready to sleep” signal, preventing the sleep system from activating. It’s not that sleep is broken; the switch simply hasn’t been triggered.
Where does the signal come from? The author believes it comes from posture.
Posture is the body’s largest sensory input system. When posture is incorrect, the body fails to properly decode the physiological signal to fall asleep, and naturally cannot enter sleep.
2. Parasympathetic Activation Mechanism
The prone sleeping position directly induces diaphragmatic breathing, which has a “rhythmic pattern.” This rhythm functions like a massage, stimulating the parasympathetic nervous network.
This network governs: relaxation, recovery, sleep, digestion, and other non-emergency physiological states.
This is not psychological, nor an act of will—it is the autonomic nervous system being triggered by posture.
Logically speaking, The Theory of Sleep Instinct redefines insomnia—or rather, asserts that “insomnia is an invalid concept.” Insomnia is not a disease, but a result of postural issues preventing the activation of the sleep switch.
Therefore, the author proposes the “Posture Hypothesis”:
The root cause of insomnia lies not in the brain, not in stress, not in psychological trauma, but in the body's failure to decode the postural signal that allows sleep to occur.
When we sleep supine, reclined, or at an angle for extended periods, the body receives a signal of “alert flatness”, a posture that, in evolutionary history, was highly vulnerable to predators. Naturally, sleep becomes difficult to initiate.
In contrast, when the body enters a prone position with the chest experiencing pressure, breathing naturally shifts to diaphragmatic breathing, which then stimulates the parasympathetic nervous system, relaxing both body and mind, thus allowing sleep to occur naturally. In other words, once the signal is realigned and reconnected, the sleep switch is activated, and sleep happens spontaneously.
✅ Core Summary:
Sleep is a human animal instinct.
It is not a disease, not a disorder, and not a learned outcome.Insomnia is the result of the body’s inability to interpret instinctive signals due to incorrect posture.
By simply adjusting posture, allowing the body to receive the correct signals again and activate the parasympathetic sleep switch, sleep will occur naturally.
No practice is needed, no self-persuasion, no reliance on external tools or medication, just trust in logic, trust in science, trust in evolution, and trust in the animal instinct already present within your own body.
This is the core of The Theory of Sleep Instinct, and the sole motivation behind the author’s construction of this entire framework: To help people rediscover sleep, an instinctive behavior essential to sustaining life.
If you want to sleep, you will fall asleep. That is also what evolution tells us.