I have found that since I have been sleeping in total darkness, even the faintest dawn light creeping in from behind the curtains (you know, that little telltale "line" of light above the window?) will wake me. I've been regularly getting 9 or more hours of sleep each night and that little light line above the curtains (this morning at 5:30) has been all I need to wake me. I use blackout curtains, so that's all the light that gets in. I used to use a blue-light led sunlight simulator (for people with S.A.D.) that had an alarm, but it wasn't gradual, so once it came on, that was all she wrote.
I got the Phillips wake up light, and its ok, but I'm too light sensitive, and even with the lowest setting, I wake up immediatley, as soona as it comes on. So it doesn't wake me up gradually at all. It's kind of annoying.
I use a lamp with a 60 watt incandescent bulb, but on the far side of the bedroom, with a timer. Sure it comes on all at once, but I don't find it that shocking.
My window also has a street light within view, so I made a big double thickness corduroy curtain, with another flap over the top above the curtain rod.
If you want something dawn-like you could get one of the compact fluorescent "soft white" bulbs which are really very yellow. A very low wattage bulb put on the other side of the room would probably be enough to wake up by.