An adherent device is configured to adhere to the skin of the patient with an adherent patch, for example breathable tape, coupled to at least four electrodes. The device comprises impedance circuitry coupled to the at least four electrodes and configured to measure respiration of the patient to detect sleep apnea and/or hypopnea. The impedance circuitry may be used to measure hydration of the patient. An accelerometer can be mechanically coupled to the adherent patch such that the accelerometer can be coupled to and move with the skin of the patient. Electrocardiogram circuitry to generate an electrocardiogram signal may be coupled to at least two of the at least four electrodes to detect the sleep apnea and/or hypopnea.