This sleep system that complements your body’s natural circadian rhythm to keep you perfectly cool or warm for a better night's sleep. Circadian rhythm causes body temperature to fall before bedtime and rise before you wake up, and this advanced system—available only from Hammacher Schlemmer—supports this natural process by automatically cooling or warming the included mattress pad to facilitate optimal sleeping temperatures. The system’s water reservoir fits under most bed frames and uses a proprietary algorithm to distribute warm or cool water to the attached mattress pad based on your age, weight, temperature preferences, and ambient temperature of the room. A free app allows you to adjust the temperature at any time from 69° F to 105° F and input personal details that allow the algorithm to optimize the sleeping temperature. The mattress pad accommodates one person and it is machine washable. App is compatible with iOS 7 and up and Android OS 4.3 and up. Pad: 36" L x 24" W x 1/4" H.