Sleep trackers are devices or applications designed to monitor and analyze sleep patterns. They typically use sensors to measure movements, heart rate, and sometimes even breathing. By collecting this data, sleep trackers provide insights into the quality and duration of sleep, helping users understand their sleep habits. Many sleep trackers can be worn on the wrist, like a smartwatch, or placed under a mattress. Some popular brands include Fitbit, Garmin, and Oura Ring. Users can access their sleep data through a connected app, which often offers tips for improving sleep quality based on the collected information.