More and more of us are experiencing this: falling asleep stretches into hours, recurring nighttime awakenings at the same time without apparent reason, or the strange sensation of being awake in an exhausted body. The alarm rings, and fatigue is already there, as if the night served no purpose. These signals, taken in isolation, may seem harmless.
But when they persist and combine over time, they paint a picture still too often addressed in fragments. Something is gradually, silently going awry. The body no longer knows how to switch to deep rest. Chronic insomnia tells a precise biological story, that of an organism remaining in a state of alert, even when everything should shut down.
What the Body Tries to Say at Night
Insomnia is not limited to difficulty falling asleep. It is part of a set of regulations that respond to and feed each other. When we observe what really happens at night, a precise organization emerges: a hyper-arousal affecting the nervous system, metabolism, immunity, and gut-brain communication.
Cortisol, the stress hormone, should significantly decrease in the evening to allow the body to shift towards recovery. In insomniacs, this cortisol remains too high during the night. Its circadian curve flattens, and this prolonged activation of the HPA axis (hypothalamic-pituitary-adrenal) prevents the shift to deep rest states. The body remains on standby, as if a danger persists.
This same activation of the HPA axis directly influences glucose metabolism. Greater nocturnal glycemic instability is observed, sometimes with hyperglycemic plateaus that fragment sleep. Insulin resistance gradually sets in, even in people whose weight remains stable. The circle closes when sleep fragmentation further exacerbates inflammation and hormonal dysregulation.
TCM Reading: The Heart and the Shen
In Traditional Chinese Medicine (TCM), the Heart houses the Shen, which can be understood as the inner presence, calm consciousness, the ability to settle. When the Heart’s Blood is insufficiently nourished or too agitated, the Shen finds no anchor. The mind turns, thoughts remain active, falling asleep becomes difficult, and sleep loses its depth.
In this reading, insomnia is not just a mind that thinks too much. It is also a terrain that no longer sufficiently nourishes inner calm. Rest begins by supporting what allows the Shen to settle: a more regular rhythm, a diet that stabilizes, fewer stimulants, less mental overload in the evening.
The Silent Inflammation That Keeps You Awake
Low-grade inflammation is one of the first observable signals. Affected individuals often present higher levels of CRP, IL-6, and TNF-α (inflammatory markers measurable in the blood). This elevation does not appear out of nowhere.
It accompanies the prolonged activation of the HPA axis and keeps the body in a state of chronic vigilance. This inflammation is not spectacular. It does not cause fever or acute pain.
But it is enough to disrupt the signals that allow the brain to switch to sleep. Pro-inflammatory cytokines interfere with the production of endogenous melatonin, the hormone that signals rest. The onset of its secretion is delayed, its amplitude reduced, its profile flattened. The central time signal loses its effectiveness, and all biological rhythms become desynchronized.
The gut-brain axis also comes into play. An increase in intestinal permeability allows the passage of LPS (bacterial lipopolysaccharides) into circulation. This metabolic endotoxemia stimulates systemic inflammation and alters the signals reaching the brain. Data on this mechanism are still emerging, but they align with the observation of persistent low-grade inflammation in many insomniacs.
TCM Reading: The Liver and Nighttime Awakenings
In TCM, the Liver governs the free flow of Qi and houses part of the Spirit when sleep comes. A tense, irritated Liver, overloaded by repressed anger, frustrations, stimulants, or late meals, blocks the movement of Qi. The wood becomes dry, it no longer bends, it resists.
The direct consequence: awakenings between 1 and 3 AM, inability to fall back asleep, restless dreams. In TCM, the Qi, the Liver’s energy, no longer flows freely: it stagnates, tenses, then rises upwards instead of allowing the necessary calm for sleep. The body remains vigilant, the mind remains attached, and the night loses its restorative function.
In practical terms: a dinner too late, too rich in carbohydrates and/or starchy foods, refined or not, or in stimulants, maintains this Liver tension instead of promoting a return to calm. Before the night, give the Liver time to lay down its burden.
When the Brain No Longer Knows How to Shut Down
The imbalance between GABAergic and glutamatergic neurotransmission completes the picture. GABA (gamma-aminobutyric acid) is the brain’s main inhibitory neurotransmitter: it slows neuronal activity and promotes sleep. Glutamate, on the other hand, stimulates brain activity.
In insomniacs, excitatory activity dominates. The VLPO (ventrolateral preoptic nucleus), this small brain structure that orchestrates falling asleep, struggles to perform its inhibitory role. Fast EEG rhythms persist during the night.
Heart rate variability is reduced, a sign of sympathetic dominance that does not sufficiently fade. Central body temperature also remains higher at the beginning of the night, delaying sleep onset. All these signals converge: the autonomic nervous system does not switch to the parasympathetic mode, the mode of recovery and regeneration.
The mitochondrial dimension deserves attention. Deep slow-wave sleep allows for the restoration of cerebral energy reserves. When this sleep is reduced or fragmented, the production of ATP (the molecule that stores cellular energy) and the balance of NAD+ (an essential cofactor for energy metabolism) are disrupted. Neurons then become less capable of maintaining stable functioning, which reinforces the reactivity of vigilance circuits.
A Consistent Mapping
These different axes do not function in isolation. Each reinforces the others: neuroendocrine hyper-arousal maintains inflammation, which worsens insulin resistance and mitochondrial dysfunction. Inflammation and endotoxemia alter neurotransmission and intestinal permeability.
The decrease in heart rate variability and melatonin maintains the system in a state of chronic wakefulness. This creates a mapping where the entire body participates in the state of insomnia. The brain does not decide alone to stay awake.
It receives signals from metabolism, the gut, the immune system, the HPA axis. All these messengers tell it the same thing: it is not safe to let go.
TCM Reading: The Spleen and Non-Restorative Sleep
The Spleen transforms food into Qi and Blood. When it is exhausted by the chronic excess of carbohydrates and/or starchy foods, refined or not, snacking, cold, or ruminated emotions, it produces Dampness and phlegm. This Dampness rises to cloud the mind: heavy but non-restorative sleep, a foggy head upon waking, a sensation of being asleep without really being so.
The Shen is like drowned in a fog. Classical tradition says that the Spleen loves stable warmth and simplicity. In practical terms: a light, warm dinner, low in carbohydrate load, without starchy foods, without cold raw vegetables, without sugar. The body can then produce clear Blood, and the Shen can settle there.
This embodied reading invites attention to concrete signals: variations in body temperature, quality of energy recovery, nocturnal glycemic stability, regularity of circadian rhythms. Rather than solely seeking to calm the mind, it becomes relevant to observe how metabolism, inflammation, and the HPA axis interact within oneself.
What These Observations Change
One might then wonder what these observations change in the approach to sleep. The answer does not lie in a list of sleep hygiene tips. It lies in the recognition that insomnia tells of a terrain that no longer knows how to regulate itself.
This terrain is built over time, through the accumulation of inflammatory, metabolic, hormonal, and nervous signals. Research documents these mechanisms with increasing precision. Studies observe robust associations between chronic insomnia and low-grade inflammation, between sleep fragmentation and insulin resistance, between nocturnal hyper-arousal and HPA axis dysfunction. These data do not always allow us to determine which comes first, but they outline a system where each element reinforces the others.
Returning to stable sleep requires retracing these threads. This involves observing what feeds inflammation, what keeps cortisol high, what fragments nocturnal glycemia, what disrupts gut-brain communication. No one can walk this path for you. But understanding the mapping allows you to know where to focus your attention.
DISCLAIMER: This article is for informational purposes only and does not replace personalized medical advice. The information presented aims to clarify documented biological mechanisms; any decision about your health, especially with medical conditions, ongoing treatment, or scheduled surgery, should be discussed with a qualified healthcare professional.
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Traditional TCM reading (Shen, Heart, Liver, Spleen, sleep): Huang Di Nei Jing (Suwen / Lingshu), classical Chinese text. This reference frames the TCM sections as a traditional reading, distinct from the biomedical block, without claiming direct clinical validation.