Slip into the tank, close the lid or hatch, lie down, and let your mind and body drift. Because small, dark spaces aren’t for everyone, some spas offer walk-in float rooms with a tub-shaped pool; newer pods often feature colored lights and music players. Dozens more are in the works, according to an informal industry survey taken last year by Float Tank Solutions, an Oregon company that helps people start float facilities. Suedfeld’s studies, which focused on how people react to restricted environments, found that floating lowers blood pressure, eases stress-related aches, and can improve athletic performance and creativity, at least temporarily. The Philadelphia area has seen at least three float centers open in the past 15 months, including Halcyon Floats, now a favorite of pro soccer player Maurice Edu. East Coast Float Spa co-owner Matt Kay became a devotee of floatation therapy three years ago after trying it in California to ease chronic hip pain from a car accident.