Sensory deprivation tanks—also called float tanks or isolation tanks—offer more than just a break from the noise of the world. These soundproof, lightless environments, filled with warm, Epsom salt-saturated water, are designed to minimize sensory input and allow the mind and body to experience deep rest. While the concept might feel futuristic or experimental, the practice is well-established and increasingly supported by clinical research.
At Altered States Wellness, float therapy is one of our foundational treatments. We’ve seen firsthand how the experience can support relaxation, mental clarity, and general well-being. But what exactly happens when someone floats? What shifts occur on a biological and neurological level when sensory input is reduced to almost nothing?
A Controlled Reduction of Sensory Input
The float tank environment is carefully calibrated to suspend normal sensory processing. The water is maintained at skin temperature, which helps blur the boundary between the body and its surroundings. The high concentration of magnesium sulfate allows the user to float effortlessly, eliminating pressure points and muscular strain. Without sound, light, movement, or physical discomfort, the brain is freed from its constant task of interpreting external stimuli.
This lack of sensory load doesn’t lead to boredom or confusion—at least not after the initial adjustment. What tends to follow is a shift into deeper brainwave states, often associated with meditation or the early stages of sleep. Most floaters report experiencing something between rest and wakefulness, sometimes referred to as a theta state. This is where interesting things begin to happen, especially within the brain and nervous system.
Neurological Effects and Brainwave Activity
Electroencephalogram (EEG) studies have observed increased theta wave activity during and after float sessions. Theta waves are typically associated with dreaming, creativity, and subconscious processing. In waking life, this state is difficult to access without structured meditation or breathwork. Inside a float tank, though, the brain seems to naturally drift toward this slower, more fluid rhythm.
This brainwave shift is often linked to a quieting of the default mode network (DMN), the set of interconnected brain regions active during mind-wandering and self-referential thought. An overactive DMN is associated with rumination, worry, and certain mood-related disorders. Reducing its activity can allow a person to feel more present and less entangled in repetitive thought patterns.
There’s also evidence that floating promotes enhanced interhemispheric communication—the ability of the two brain hemispheres to synchronize and share information. This synchronization may support creative problem-solving and a feeling of cognitive reset after a float session.
The Role of the Autonomic Nervous System
Another layer of the experience involves the autonomic nervous system, which controls involuntary processes like heart rate, digestion, and stress response. The environment inside a float tank helps shift the nervous system from sympathetic dominance (associated with fight-or-flight) into parasympathetic mode (associated with rest-and-digest).
Heart rate and blood pressure often drop during a session. Cortisol, the body’s primary stress hormone, may also decrease. At the same time, the body may release endorphins and other neurochemicals linked to mood balance and physical ease. This nervous system shift explains why many people emerge from float sessions reporting not just mental clarity, but also a tangible sense of calm that can last for hours or even days.
Musculoskeletal and Physical Support
The physical benefits of float therapy begin with the unique properties of magnesium sulfate, also known as Epsom salt. This mineral compound is widely used to support muscle recovery and reduce tension. Absorption through the skin during floating is a possibility, though the degree of absorption varies and is still under investigation. Regardless, the buoyancy created by the high salt concentration allows the body to fully relax without the pull of gravity.
Muscles that are usually engaged to hold posture or balance can release, giving overworked areas of the body—especially the neck, shoulders, and lower back—a chance to rest in ways that other modalities can't always provide. Athletes often turn to floating for recovery, noting improvements in soreness, fatigue, and even sleep quality after regular use.
Sensory Reset and Mental Recalibration
Many floaters describe a “reset” feeling after their session. This goes beyond physical relaxation—it’s as though the mind reorganizes itself. Without the constant alerts, messages, and visual clutter that dominate modern life, the brain can prioritize deeper processing.
Some people report bursts of insight, spontaneous memory retrieval, or a surge of creative ideas during or after a float. Others simply feel more emotionally balanced and mentally clear. Part of this can be attributed to the theta state and its effects on cognition, but there’s also a psychological aspect: for once, the mind is not bombarded with input. It can finally hear itself think.
Regular floating may help reduce the mental noise and overstimulation many people live with. Over time, this can translate to better focus, more effective stress management, and a greater sense of internal stability.
Emerging Research and Clinical Studies
Recent studies are starting to validate what many floaters have experienced anecdotally for years. Clinical trials have examined float therapy in relation to anxiety, PTSD, depression, and chronic stress—with promising results.
One 2018 study published in PLOS ONE found that a single one-hour float session significantly reduced symptoms of anxiety and improved mood in participants with high levels of stress and anxiety disorders. The effects were observed immediately post-float, and the authors noted the unusual consistency of positive outcomes across a varied group of individuals.
Other research has looked at float therapy’s impact on sleep. While not a treatment for insomnia, some users experience better sleep quality and sleep onset after regular float use, possibly due to the parasympathetic response and cortisol regulation.
What makes float therapy especially interesting to researchers is that it produces noticeable effects without introducing an external chemical, device, or stimulant. It’s a passive, self-directed experience that seems to activate the body’s own ability to shift states.
The Psychological Importance of Stillness
Stillness is often undervalued in wellness routines. The modern nervous system is rarely given a chance to fully pause. Even when we rest, we’re often scrolling, listening, watching, or planning. Sensory deprivation offers a rare opportunity for stillness—not just physical, but neurological.
In the absence of external input, the mind begins to settle. Thoughts slow, awareness deepens, and a subtle sense of spaciousness can emerge. For some, this is deeply meditative. For others, it brings a level of relaxation they haven’t accessed in years.
This psychological stillness can be grounding, especially for those managing chronic stress or cognitive overload. Many floaters begin to notice emotional patterns or insights that would typically be drowned out by daily noise. Over time, this can support emotional regulation and personal reflection.
Final Thoughts
Sensory deprivation tanks aren’t magic, but they do offer something rare: a chance to experience ourselves without distraction. The research continues to evolve, but what we already know points to a powerful combination of neurological, physiological, and psychological effects—all from an experience that involves doing almost nothing.
Floating encourages the body to rest, the brain to recalibrate, and the mind to let go. Whether someone is seeking relief from chronic tension, support for mental clarity, or simply a deeper kind of rest, the science of sensory deprivation suggests this quiet practice has something to offer.
