Zs

Sleep cycles for people are typically 90 minutes. Based on that and the current time, Zs calculates when you should set your alarm so that you don't interrupt that natural rhythm (with a little buffer to account for getting into bed and falling sleep, of course).

Using Zs, you'll know when to set your alarm so that you're using your body's natural flow instead of working against it. You should wake up feeling refreshed even if you could've slept just a little bit more. If you wake up as part of your natural sleep cycle, you're less likely to experience that early morning grogginess and can start your day quickly.