What's the best iOS app for tracking sleep patterns and waking up gently?

Sleep Cycle is a sleep tracking app that focuses on monitoring sleep patterns and providing a gentle wake-up experience. It uses movement detection through the phone's accelerometer, which can be placed on the nightstand or under the pillow, to analyze sleep cycles and identify phases like deep or light sleep. This data helps users track sleep quality over time and spot trends that might affect rest. A key feature is the smart alarm, which allows setting a wake-up window—typically 20 to 30 minutes—to rouse users during lighter sleep stages, minimizing grogginess. The app also includes sleep sounds to aid relaxation and a no-snooze alarm that requires physical interaction to turn off, encouraging immediate rising. Reviews indicate high satisfaction with the free version's functionality, though some users note that the wake window might not suit tight schedules. Overall, Sleep Cycle is effective for those seeking to understand and improve their sleep without invasive hardware.