For iOS: To view your sleep data,
1) Find Sleep under the blue crescent moon on the home screen and tap on it.
2) Slide finger in an upward motion on the home screen.
Either option will show the lower half of the home screen, where sleep data is available.
For Android: To view your sleep data, locate the Sleep panel in the middle of the home screen. To access additional data, tap the same panel and view lower half of the screen.