Sleep

Sleep is not a passive shutdown but an active, energy-dependent state of inhibition, and its disturbance—insomnia—is fundamentally a problem of low metabolic energy and the consequent stress response. 2 Ray Peat argued that the brain, like a muscle, must restore its energy to relax, and that the inability to enter deep, restorative sleep stems from a failure of mitochondrial energy production, most commonly driven by hypothyroidism. 2 In this low-energy state, the liver cannot store adequate glycogen to supply the brain with glucose through the night, triggering a cascade of excitatory stress hormones. 4

As blood glucose falls during the night, the body releases adrenaline, histamine, cortisol, and serotonin in sequence to mobilize energy, each of which promotes wakefulness and prevents the descent into deep sleep. 2 Peat noted that hypothyroid individuals, studied with brainwave analysis, never progress beyond the superficial second phase of sleep, waking unrested and achy. 4 This nocturnal stress response is compounded by the liberation of polyunsaturated free fatty acids from fat stores, which block glucose oxidation, increase inflammatory prostaglandins, and create an excitatory state that further interferes with both slow-wave and REM sleep. 7 The rise of these stress mediators explains why insomnia is so pervasive in aging, as the chronic adaptation of low thyroid function leads to a nightly overproduction of adrenaline and cortisol. 10

The most common root cause of this metabolic disruption, Peat maintained, is intestinal irritation and the absorption of endotoxin from bacteria, which increases systemic histamine and serotonin. 2 Poor digestion, heavy evening meals rich in fat, and the consumption of starches that feed bacteria can all promote endotoxin formation, making the digestive system a primary source of the irritation that drives nighttime adrenaline. 2 Peat also identified estrogen as a powerful disruptor of sleep, recounting cases where simply discontinuing estrogen therapy immediately restored normal sleep, and noting that stress of any kind activates the aromatase enzyme, shifting the steroid balance toward estrogen and away from protective hormones. 2

Therapeutic interventions center on restoring oxidative energy production and blunting the stress response. Peat reported that a very small dose of T3 (5-10 mcg) at bedtime often produces sleep within minutes by rapidly increasing the rate of energy production, an effect one colleague described as "better than morphine." 2 Progesterone and thyroid work in concert to keep body temperature up, maintain liver glycogen stores, and directly shift the balance away from cortisol, histamine, serotonin, and adrenaline. 4 Practical dietary supports include salty and sugary snacks at bedtime—such as milk with honey or ice cream—to stabilize blood glucose and lower adrenaline, while aspirin at bedtime can inhibit the synthesis of wakefulness-promoting prostaglandins. 2 Georgi Dinkov has added that testing for a deranged diurnal cortisol pattern, elevated nighttime catecholamines, or a TSH above 3 can help identify the specific stress mediators driving an individual's insomnia. 8

Peat distinguished between the naturally quiet resting state of energized cells and the state of protective inhibition that prevents injury from overstimulation and fatigue, arguing that true sleep is only possible from the former. 3 When energy production fails, the organism enters a catabolic state during sleep, with increased growth hormone, prolactin, parathyroid hormone, and inflammatory cytokines that break down tissue rather than restoring it. 7 This framework explains why stimulants like caffeine can paradoxically improve focus in the hypothyroid by temporarily raising brain energy, but only the restoration of oxidative metabolism through thyroid hormone, a supportive diet, and the reduction of intestinal endotoxin can produce the deep, restorative sleep that allows genuine physiological regeneration. 2