All Samsung Galaxy devices have a feature built in, called "blocking mode". Swype down your notification bar with TWO fingers to bring up...
from there, long press on the blocking mode icon
from there you can set it up accordingly
even what time of the day you'd like it to turn itself on or off.
works great!
The only thing that bothers me is its inability to turn off your LED notifications if you have that activated on your device.
Personally, I have to have a completely dark room in order to sleep well, and the light from my phone is what actually wakes me up each morning (before the actual alarm does).
Everything else works great though and you can also set it up to allow certain contacts to ring or text through for emergency purposes.
Only downside is, it doesn't turn off that flashing LED, but I simply turn it off manually when I activate my alarm, takes two seconds.
S5 tap'n