NASA has a critical requirement for a wearable device that can provide objective measures of sleep and activity for its crew during long duration spaceflight. In the proposed program, we will develop an unobtrusive wrist worn monitor that places minimum burden on the crew in operating the device. The device, once worn, requires no action from the crew and automatically records and analyzes actigraphy and sleep data. The device will have battery life of about one year and wireless data transfer so the crew will not be burdened with recharging the device and downloading data from the device. The monitoring device will provide real-time feedback on the level of activity and duration and quality of sleep. The proposed device is based on an existing sleep and activity monitor which we will modify and enhance to make it suitable for use in spaceflight environments. Data format, including epoch length and sleep statistics provided by the proposed system will conform to formats currently used in sleep research. In Phase 1, we will deliver a set of fully functional devices that can be deployed in spaceflight analogs. We will also perform feasibility studies of a Phase 2 unit, which will measure, in addition to sleep, activity and heart rate, other physiological parameters such as heart rate variability, blood pressure, vasoconstriction, pulsewave velocity, and electrodermal activity. Since the work is based on an existing sleep and activity monitoring platform, we expect that the Technology Readiness Level (TRL) of the Phase 1 unit to be at 7, and the Phase 2 unit to be at 8.