If you're among the millions of Americans who suffer from overstimulation, forget unplugging your phone and try unplugging your senses. At Float Matrix, you can escape your worries and your gadgets in a unique way: in a sensory deprivation tank. The typical flotation tank is a soundproof, lightproof pod where you bob around in about a foot of warm, salt-saturated water. (A one-hour session costs $75 for one person, $125 for two.) The reputed health benefits include alleviation of back pain and improved concentration. An added plus? It's an effortless way to produce endorphins. Whether you choose to lie back and take a nap, or simply engage in idle fantasy, expect to be buoyed by the kind of euphoric rush you might get from, say, an hour of yoga.