Determining different sleep stages in a wearable medical device patient

A patient monitoring device configured to monitor cardiac activity and sleep stage information of a patient, the device comprising:

• a plurality of electrodes configured to be coupled externally to a patient to acquire electrocardiogram (ECG) signals from the patient and provide a therapeutic shock to the patient in response to detection of a cardiac arrhythmia, the patient monitoring device configured to provide for the detection of the cardiac arrhythmia based on one or more cardiac arrhythmia detection parameters;
• at least one motion sensor configured to generate at least one motion signal based upon movement of the patient;
• a cardio-vibrational sensor configured to generate a cardio-vibrational signal of the patient;
• and
• at least one processor operably coupled to the plurality of electrodes and the at least one motion sensor, the at least one processor configured to
• receive the at least one motion signal from the at least one motion sensor and derive one or more motion parameters from the at least one motion signal,
• receive the ECG signals from the plurality of electrodes and derive one or more ECG parameters from the ECG signals, the one or more ECG parameters comprising at least one heart rate parameter,
• determine whether the patient is in an immobilized sleep stage or a non-immobilized sleep stage based upon analysis of the one or more motion parameters and the one or more ECG parameters comprising the at least one heart rate parameter,
• adjust the one or more cardiac arrhythmia detection parameters such that the patient monitoring device operates in a first monitoring and treatment mode when the at least one processor determines that the patient is in the immobilized sleep stage,
• commence monitoring the cardio-vibrational signal of the patient when the at least one processor determines that the patient is in the immobilized sleep stage, wherein monitoring the cardio-vibrational signal of the patient includes determining one or more electromechanical parameters of a heart of the patient using the cardio-vibrational signal, and
• monitor the patient for the cardiac arrhythmia using the first monitoring and treatment mode.