Stasis, in the sense of pausing or dramatically slowing biological activity, is already possible in limited forms. Doctors routinely cool patients to slow their metabolism after cardiac arrest, and an ongoing surgical trial is pushing further by chilling trauma patients to around 50°F (10°C) to buy time for emergency repairs. True long-term suspended animation, the kind depicted in science fiction where someone sleeps for years and wakes up unchanged, remains out of reach. But the gap between what exists today and what researchers are working toward is narrowing faster than most people realize.
What “Stasis” Actually Means
The word stasis simply means a state of inactivity or equilibrium. In medicine, it usually refers to slowed or stopped flow, like blood pooling in the veins (venous stasis). But when most people search for whether stasis is possible, they mean something closer to suspended animation: slowing the body’s metabolism so dramatically that aging, oxygen demand, and cellular activity nearly stop, then restarting everything later without damage.
That distinction matters because the challenges are completely different depending on how deep and how long you want the pause to last. Cooling someone for 24 hours after a heart attack is a solved problem. Preserving a person for months or years is not. The science sits on a spectrum, and the current frontier is somewhere in the middle.
What Already Works: Therapeutic Cooling
The most established form of human stasis is targeted temperature management, used in hospitals worldwide. After cardiac arrest, doctors cool patients to between 32°C and 34°C (about 89°F to 93°F) and hold that temperature for 12 to 24 hours. This slows the brain’s demand for oxygen and reduces the cascade of damage that follows interrupted blood flow. Afterward, the body is rewarmed at a controlled rate of roughly half a degree Celsius per hour to avoid complications.
This isn’t dramatic sci-fi stasis. The patient’s metabolism is only modestly reduced, and the window is measured in hours. But it works. It improves survival and neurological outcomes after cardiac arrest, and it’s been standard practice for years.
Emergency Preservation: Deeper and Colder
The most ambitious human trial right now goes much further. The Emergency Preservation and Resuscitation for Cardiac Arrest from Trauma (EPR-CAT) trial, led by surgeon Samuel Tisherman at the University of Maryland, targets patients with penetrating trauma (like gunshot or stab wounds) who lose a pulse within five minutes of arriving at the hospital and don’t respond to standard resuscitation.
These patients would otherwise die. The procedure involves flushing cold saline through the body to drop core temperature to around 50°F (10°C), far below the therapeutic hypothermia range. At that temperature, cellular activity slows to a crawl. The surgical team then has time to repair the damage before rewarming the patient and restarting the heart. The trial is enrolling 10 EPR patients and 10 controls, with the primary goal of measuring survival to hospital discharge without major neurological deficits.
Because these patients are in cardiac arrest from acute trauma, they cannot give informed consent. The trial operates under an FDA exception for emergency research, with extensive community consultation beforehand. It represents the closest thing to true suspended animation ever attempted in humans, though the window is still measured in hours, not days or years.
Nature Already Solved This Problem
If you want proof that deep biological stasis is physically possible, look at tardigrades. These microscopic animals can enter a state called cryptobiosis, where metabolic activity drops to undetectable levels. They survive extreme dehydration, radiation, and temperatures near absolute zero, then rehydrate and resume normal life.
The mechanism is remarkably well understood. When a tardigrade enters its dormant “tun” state, it floods its cells with a sugar called trehalose, which reaches concentrations of about 18.7% of its dry weight. Trehalose physically replaces water molecules around proteins and cell membranes, locking structures in place like biological glass. At the same time, specialized protective proteins ramp up to 12 times their normal levels, shielding DNA and stabilizing cellular architecture. When water returns, these changes reverse, and the animal wakes up.
Humans don’t produce trehalose in meaningful amounts, and we lack the protective proteins tardigrades rely on. But this molecular toolkit is a blueprint. Researchers studying organ preservation and whole-body stasis are actively trying to replicate these effects with synthetic compounds.
Drugs That Slow Metabolism
One of the most promising frontiers is pharmacological stasis: using drugs to push cells into a low-energy state without cooling. A 2024 study published in eLife identified a compound called SNC80 that rapidly and reversibly slows metabolism in living tissue. Hearts treated with SNC80 during machine perfusion dropped their oxygen consumption to less than 50% of normal and sustained that reduction over six hours, all while maintaining tissue viability.
What makes this finding especially interesting is the mechanism. SNC80 was originally developed to activate opioid receptors, but the metabolic slowing turned out to be unrelated to that activity. Researchers created a modified version with almost 1,000 times less opioid receptor binding that still slowed metabolism just as effectively. This means the effect can potentially be separated from the sedation and other side effects of opioid drugs.
Other compounds under investigation include hydrogen sulfide (which induces a hibernation-like state in rodents) and various synthetic peptides that mimic natural torpor signals. None are ready for human use, but the goal is clear: a drug that could be administered to a trauma patient, an organ awaiting transplant, or eventually an astronaut on a long-duration mission to dramatically reduce biological activity on demand.
Why Long-Term Stasis Is Still So Hard
The biggest obstacle to extending stasis from hours to months or years is ice. Cooling tissue slowly enough for conventional freezing allows ice crystals to form inside and between cells, puncturing membranes and destroying structure. The alternative is vitrification: cooling so rapidly, with the help of chemical protectants, that water solidifies into a smooth, glass-like state without forming crystals at all.
Vitrification works well for small samples like embryos and sperm. For whole organs, it gets much harder. The critical warming rate needed to avoid ice formation during rewarming is typically 10 to 1,000 times faster than the cooling rate required to vitrify in the first place. If rewarming is too slow, ice crystals form on the way back up. If it’s uneven, thermal stress causes cracking. A 2023 study in Nature Communications demonstrated successful vitrification and transplantation of rat kidneys using nanoparticle-based warming to solve the uniformity problem, but scaling this to human organs, let alone whole bodies, remains a major engineering challenge.
Even without ice, there’s the question of what happens to cells held in metabolic limbo for extended periods. DNA accumulates damage. Membranes degrade. Proteins slowly unfold. Tardigrades have millions of years of evolutionary solutions for these problems. Humans do not, and replicating that protection artificially across trillions of diverse human cells is an unsolved problem of enormous complexity.
Space Travel and the 90% Question
NASA and the European Space Agency have both funded research into induced torpor for deep space missions. The rationale is straightforward: a crew in a hibernation-like state would need up to 75% less food and water, dramatically reducing spacecraft payload. The psychological benefits of sleeping through a six-month Mars transit are obvious too.
From a purely comparative physiology standpoint, humans burn energy at roughly 1 watt per kilogram of body weight. Hibernating mammals of similar size can drop that by 90% or more. The theoretical room for reduction exists. The practical question is whether humans, who did not evolve to hibernate, can be safely guided into and out of such a state. Short-term therapeutic cooling shows the body tolerates modest metabolic reduction well. Whether deeper, longer suppression is survivable without organ damage or cognitive impairment is unknown.
The most realistic near-term scenario for space torpor involves mild cooling combined with pharmacological metabolic suppression, held for days or weeks at a time with periodic waking intervals. This wouldn’t be the decades-long stasis of interstellar fiction, but it could make Mars missions significantly more feasible.
Where Things Stand Right Now
Stasis exists on a sliding scale. At one end, therapeutic cooling after cardiac arrest is routine medicine. In the middle, emergency preservation at 50°F is being tested in human trauma patients. Further out, pharmacological agents can halve an organ’s metabolic rate for hours. At the far end, long-term whole-body preservation through vitrification remains theoretical for humans, though individual organs are getting closer in animal models.
The short answer: limited stasis is not only possible but already saving lives. Deep, long-duration stasis of the kind most people imagine when they ask this question is not yet achievable, but every major biological barrier to it is under active investigation, and several have partial solutions that didn’t exist a decade ago.