Various systems, devices, and methods for contactless sleep tracking are presented. Based on data received from a contactless sensor, such as a radar sensor, determine that a user has entered a sleep state. A transition time may be determined at which the user transitions from the sleep state to an awake state. An environmental event, based on data received from an environmental sensor, may be identified as occurring within a time period of the transition time. The user waking may be attributed to the environmental event based on the environmental event occurring within the time period of the transition time. An indication of the attributed environmental event as a cause of the user waking may be output.