📐 Logical Steps Leading to the “Posture Hypothesis”
In the construction of The Theory of Sleep Instinct, the “Posture Hypothesis” forms a critical component of the overall model. The author did not arrive at this hypothesis through arbitrary speculation, but through a series of purely logical and technical reasoning steps. This article will outline the technical inference methods used to derive the “Posture Hypothesis,” relying entirely on logical structure and engineering-style deduction, without reference to personal emotions, religious beliefs, or cultural customs.
1🟥 Analogical Reasoning
The author first applied analogical reasoning by comparing sleep behavior to other clearly observable instinctive behaviors.
For example: the act of eating requires the specific physiological posture of opening the mouth in order to be triggered; defecation requires a particular squatting or straining posture. These examples demonstrate that instincts are not activated automatically, but are triggered through a combination of “posture + physiological signals.”
Therefore, it is reasonable to draw an analogy: the instinct of sleep also requires a specific posture as a triggering signal, this is the starting point of the “Posture Hypothesis.”
2🟧 Deductive Reasoning (Deductive Elimination)
Based on the major premise that “sleep is an instinctive behavior preserved by evolution,” the author applies deductive reasoning:
- If sleep is instinctive, then all organisms should be able to fall asleep naturally;
- However, the widespread insomnia seen in modern humans suggests that some element is disrupting this instinctive mechanism;
- If we eliminate structural brain issues (since the human brain structure has not fundamentally changed) and rule out abnormal external environmental interference, then the most likely factor is that “human physical posture” has altered the original signal input.
This is a classic form of deductive reasoning, starting from a premise, excluding illogical factors, and ultimately converging on “posture” as the only reasonable variable.
3🟨 Reductio ad Absurdum
The author further applies reductio ad absurdum by assuming the mainstream view—that insomnia is a pathological phenomenon—is true. For example, suppose insomnia is caused by academic or work-related stress. In that case, we are unable to explain why, during extended periods of insomnia, patients can still unexpectedly fall into deep sleep during daily life. The stress is presumably still present, so this outcome is logically inconsistent.
4🟩 Functional Reduction
The author attempts to reduce the complex phenomenon of “insomnia” to a functional impairment rather than a disease.
Just as the body cannot enter feeding mode without opening the mouth, if the posture is incorrect, the body cannot recognize the signal that “it’s time to sleep.”
In other words, insomnia is not a malfunction of the brain or nervous system, but a case of “switch not activated” (signal decoding failure):
The body does not receive the postural signal → sleep response (parasympathetic activation) cannot be triggered.
This approach reduces the problem to a functional disconnect between signal and response, avoiding unnecessary pathological interpretations.
5🟪 Evolutionary Inference
The author uses evolutionary theory as a tool to reason that instinctive behaviors could not have been designed apart from the principles of being “simple, reliable, and physically controllable.”
It is implausible for any instinctive behavior to depend on abstract concepts (such as willpower or ideas) in order to be activated.
Since sleep is a basic function filtered through long-term animal evolution, it is highly likely, just like eating—that it is triggered by a kind of primitive physical action.
This forms a logical framework starting from the premise that “evolution could not have designed it that way,” leading to the inference that “there must be a clear triggering condition.”
6🟫 Systematic Signal Modeling (Signal Decoding Modeling)
Furthermore, the author translates the overall logic into an engineering-style model:
Posture (prone sleeping) → thoracic compression → induction of diaphragmatic breathing → activation of the parasympathetic nervous system → body enters sleep mode.
This forms a complete system architecture of:
Signal input → decoding → physiological response → behavioral outcome.
It aligns with engineering design logic, is reproducible, verifiable, and possesses a logically closed structure.
7🟦 Prone Sleeping in Infants as Evidence of Instinct (Instinctive Infant Behavior)
Finally, what further supports the “Posture Hypothesis” is the instinctive behavioral choices of infants.
“If left uninfluenced by external forces, infants will naturally sleep in a prone position.” This is not the result of training, nor of medical knowledge, it is pure biological instinct.
The prone sleeping behavior of infants proves that “instinctive sleep” is linked to a specific posture from birth.
From this, it is reasonable to deduce:
- If infants are suited to prone sleeping → adults are also suited to prone sleeping;
- Furthermore, adults possess stronger neural regulation and muscular control, and may in fact be “even more suited to prone sleeping” than infants.
This reflects the continuity of animal instinct: instinct does not disappear with age, it is merely suppressed by incorrect habits.
🧩 Conclusion: This Is Not Intuitive Guesswork, But the Result of Systematic Reasoning
All of the above reasoning points belong to the domain of pure logic and technical inference, with none derived from personal emotion or subjective belief.
The “Posture Hypothesis” proposed by the author is not a random guess or hindsight bias, but the conclusion of a complete chain of logical reasoning.
This is also why the author repeatedly emphasizes:
- Sleep is not achieved through willpower, it is triggered by instinctive signals.
- If the signal is incorrect, sleep will be disrupted.
- If the signal is correct, sleep will occur automatically.
“Posture” is the starting point of that signal.
Charles Darwin was a 19th-century British naturalist, geologist, and biologist, best known for proposing the theory of evolution. In 1859, he published On the Origin of Species, in which he systematically argued that species evolve gradually through the process of natural selection. This view challenged the then-dominant belief that species were fixed and unchanging, and had a profound impact on biology and human thought.