Sleep Cycle - Bio-alarm clock that wakes you up at optimal times based on your sleep patterns.
Sleep as Android - Common alarm clocks ignore your sleep cycles, they wake you on schedule no matter your are currently in your deep sleep. Waking up from deep sleep is unpleasant, it makes you tired and it may negatively affect your productivity during the whole day.
Talalarmo - Minimalistic android alarm
Pillow for iOS - An iOS companion that helps you sleep better 💤
Puzzle Alarm Clock - Puzzle Alarm Clock is an Android-based application which gives a very different sleep monitoring services and an alarm clock module that works according to the user’s requirement.
Gentle Alarm - Gentle Alarm can consider your sleepcycles to wake you up when you are in light sleep.