There’s a number of apps that actually help with this; I used to use SleepCycle, not sure if that one’s still good. Basically, you set up the app and tell it how long you want to sleep, then set the phone on the side of the bed. It uses the accelerometer to detect when you fall asleep, and how deeply you’re sleeping (there’s some that use fitness bands or other monitoring tools, if you use them), and will wake you up close to your desired wake time, when you’re in light sleep / between REM cycles. For instance, if you set the alarm for 2 hours, it might wake you up after 1 hr 45 minutes, if that’s when you’re sleeping lightly, rather than wait the full 2 hours and wake you up in the middle of a deep sleep.
The end result is that you don’t get those times when your alarm goes off and you feel awful, as that’s typically caused by an interrupted REM cycle.
There’s a number of apps that actually help with this; I used to use SleepCycle, not sure if that one’s still good. Basically, you set up the app and tell it how long you want to sleep, then set the phone on the side of the bed. It uses the accelerometer to detect when you fall asleep, and how deeply you’re sleeping (there’s some that use fitness bands or other monitoring tools, if you use them), and will wake you up close to your desired wake time, when you’re in light sleep / between REM cycles. For instance, if you set the alarm for 2 hours, it might wake you up after 1 hr 45 minutes, if that’s when you’re sleeping lightly, rather than wait the full 2 hours and wake you up in the middle of a deep sleep.
The end result is that you don’t get those times when your alarm goes off and you feel awful, as that’s typically caused by an interrupted REM cycle.
YMMV, but they work fantastically for me.