The recent return to so little sunshine had me reflecting on a wake-up combo that’s so subtle I enjoyed it for years without really recognizing it. I use a dawn-simulating BioBrite alarm clock along with a programmable thermostat (anyone who has central HVAC without a programmable thermostat these days is just missing out). The combination of light and warmth really gets me awake at consistent times in the morning without really relying on any audio cues. The BioBrite can also be adjusted to increase the light output over longer periods of time (15/30/60/90 minutes), reversed to simulate dusk, or be used as a nightlight.
In the winter, having light come up along with heat is the most natural way to ease back to consciousness that I can imagine.