Waking up gradually is generally conducive to better sleep, and regular alarms sure aren't manufactured for gradual wakings. In a perfect world, we'd all rise when the sun tells us to and be healthier for it, and this is the closest you can get to that.
Promising review: "With this, I can leave my phone charging across the room (or in a handbag, even) and set this little to set 15, 30, 45, or 60 minutes later. Then, I get in bed and read a book for an hour. This sun goes down gradually, and I go to bed. Eight hours later, it rises gradually, so much so you won't even notice it at the beginning. You can set sounds to compliment the sunrise like birds chirping, ocean waves, classical music, or FM radio (although why on Earth would you choose FM radio?). It doesn't even feel right to call this an alarm, because it's not obnoxious or loud. It doesn't jolt you awake. This thing is perfect. I'm reading more, sleeping a lot better, and I don't even care about grabbing my phone to check social media in the mornings." —Mimi 5000
Get it from Amazon for $97.99.