If you want an app to calculate your own sleep needs and generate a schedule to get the most rest, RISE is a top contender. The app uses phone history data to calculate your sleep debt and circadian rhythms, then offers advice on how to sleep better and live better. It integrates with many popular wearables and is geared toward helping you pay off your sleep debt and schedule your day.
Another good option is Sleep Cycle, which analyzes your sleep patterns to wake you up during your lightest phase so you can get the most rest. It also has resources on sleep-related topics like insomnia and sleep disorders, so it's a good choice if you want a sleep app that's good for sleep and not just sleep.
If you want something more experimental, Pzizz offers personalized dreamscapes using psychoacoustic techniques to help you fall asleep and stay asleep. With customizable soundscapes and a hybrid music system, Pzizz can help you relax and wake up feeling rested, which is great for people who have trouble falling asleep or staying asleep.
Last, Endel offers adaptive soundscapes based on real-time data like the time of day and heart rate. The app is designed to help with sleep and other activities, and has been scientifically validated to improve focus and reduce stress, so it's a good choice for anyone who wants to improve their overall well-being and sleep.