A method for detecting sleep for continuous positive airway pressure (CPAP) therapy is disclosed. Discrete values of a control signal generated by a pressure controller to regulate delivered pressure at the patient are measured over a predefined time window encompassing one or more respiratory cycles. A baseline control signal value is generated from a weighted average of the measured discrete values of the control signal. Estimates of a respiratory cycle period, an inspiration control time, and an expiration control time are then generated. Estimates of one or more secondary control signal properties for each of the respective inspiration control time and expiration control time are generated. Pressure to the patient is increased in response to an evaluation of the estimates of the one or more secondary control signal properties being indicative of the patient reaching a sleep state.
