SleepBot - SleepBot is a sleep tracking app available in Google Play and the Apple App Store.
KClock Clock - Universal clock application for desktop and mobile Linux
Simple Alarm Clock - Simple open source alarm application for Android devices.
Gnome Clocks - Clock application designed for GNOME 3
Clock + - Alarm clock, timer, and stopwatch application for Android
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.