I just started using that feature on some smart watches that wakes you up when you're in light sleep within 30 minutes of your alarm, and DANG--game changer, seriously. For the last few mornings I've woken up feeling better after six hours of sleep than on a lot of mornings where I've had a hard wakeup after nine.
EDIT: It's called "Smart Wake" on Android and Garmin watches, it's an app like "AutoWake" for Apple Watch, and it's "Smart Alarm" for Pebble.