What are some alternatives?
When comparing Calm and Sleep as Android, you can also consider the following products
Headspace - Meditation made simple. Brilliant things happen in calm minds.
SleepBot - SleepBot is a sleep tracking app available in Google Play and the Apple App Store.
Simple Habit - Our mission is to empower humans to stress less, achieve more, and live better. Meditate today!
Talalarmo - Minimalistic android alarm
Smiling Mind - Promotes mindfulness and meditation for young people
Gentle Alarm - Gentle Alarm can consider your sleepcycles to wake you up when you are in light sleep.