Abstract: An apparatus for monitoring a user's health and/or sleep and/or the efficacy of a treatment (e.g. a sleep treatment or other type of health treatment) can include use of a wearable electronic device. The device can include an array of sensors for collecting user data. The user data can be used by the device to evaluate criteria related to the user's health to monitor efficacy of a treatment. In addition, or alternatively, the collected data can be transmitted to a central server and/or input/output device for evaluating different criteria for monitoring the user's health and/or sleep as well as the efficacy of a treatment being provided to the user.