What's the best iOS app for tracking sleep quality and getting personalized insights to improve it?

Fitbit is a robust health and fitness application that stands out for its advanced sleep tracking capabilities. The app monitors sleep stages, including REM, light, and deep sleep, along with restlessness levels, to generate a comprehensive sleep score. This data helps users identify patterns, such as insufficient REM sleep or frequent awakenings, which can explain daytime fatigue. For instance, one user discovered through the app that despite getting eight hours of sleep, high restlessness was impacting rest quality, leading them to adjust their supplement routine with magnesium for better results. Features like nightly sleep reports and personalized recommendations make it practical for real-world use, whether for optimizing bedtime routines or addressing chronic sleep issues. However, some limitations exist, such as the need for a Fitbit device for full functionality and occasional navigation hurdles in the subscription settings, as noted in reviews where users struggled to cancel premium plans. Despite this, the app's intuitive design and data-driven insights provide valuable support for sleep improvement, with many users reporting heightened awareness and positive changes in their sleep habits.