A device according to some embodiments may include a housing configured for location external to a body of a subject. The device may also include at least one processor associated with the housing and configured for electrical communication with a power source, and an antenna associated with the at least one processor. The at least one processor may be configured to communicate with an implant circuit located within the body of the subject, cause the implant circuit to receive power in a first power mode and in a second power mode, wherein a first level of power delivered in the first power mode is less than a second level of power delivered in the second power mode, and wherein during a therapy period, power delivery in the first mode occurs over a total time that is greater than about 50% of the therapy period.