A system for controlling a therapy based upon a sleep state of a patient, the system comprising: - a stimulation generator, - a sensing module, - a telemetry module, - a sleep stage detection module, - a memory, - one or more stimulation electrodes for stimulating brain tissue, - a recording electrode for detecting brain neuronal activity, and - a processor operationally coupled with the simulation generator, the sensing module, the telemetry module, the sleep stage detection module and the memory, the memory configured for storing instructions for execution by the processor and information defining therapy delivery for the patient, wherein the instructions for execution by the processor comprise instructions to: - control the one or more stimulation electrodes to emit stimuli to brain tissue that comprises a signal that is produced from a stimulation frequency spectrum having a power spectral density per unit of bandwidth proportional to 1/f β, wherein β excludes 0, - determine whether the patient is in a sleep state, - determine a sleep stage of the sleep state based on a biosignal detected from the recording electrode, - determine a patient's frequency spectrum based on a biosignal detected from the recording electrode, and - adjust the stimulation frequency spectrum if during a given sleep stage the patient's frequency spectrum changes. - a stimulation generator, - a sensing module, - a telemetry module, - a sleep stage detection module, - a memory, - one or more stimulation electrodes for stimulating brain tissue, - a recording electrode for detecting brain neuronal activity, and - a processor operationally coupled with the simulation generator, the sensing module, the telemetry module, the sleep stage detection module and the memory, the memory configured for storing instructions for execution by the processor and information defining therapy delivery for the patient, wherein the instructions for execution by the processor comprise instructions to: - control the one or more stimulation electrodes to emit stimuli to brain tissue that comprises a signal that is produced from a stimulation frequency spectrum having a power spectral density per unit of bandwidth proportional to 1/f β, wherein β excludes 0, - determine whether the patient is in a sleep state, - determine a sleep stage of the sleep state based on a biosignal detected from the recording electrode, - determine a patient's frequency spectrum based on a biosignal detected from the recording electrode, and - adjust the stimulation frequency spectrum if during a given sleep stage the patient's frequency spectrum changes. - control the one or more stimulation electrodes to emit stimuli to brain tissue that comprises a signal that is produced from a stimulation frequency spectrum having a power spectral density per unit of bandwidth proportional to 1/f β, wherein β excludes 0, - determine whether the patient is in a sleep state, - determine a sleep stage of the sleep state based on a biosignal detected from the recording electrode, - determine a patient's frequency spectrum based on a biosignal detected from the recording electrode, and - adjust the stimulation frequency spectrum if during a given sleep stage the patient's frequency spectrum changes.