I have bought a Lumie Dawn Simulator lamp.
I have used it now for six nights and I wish I'd bought it years ago! You set it for half an hour before you want to waken and 'softly, progressively, it simulates the appearance....of a natural sunrise, the signal to which your emotional brain has been wired to awaken during millions of years of evolution on earth.' (David Servan-Schreiber in Healing Without Freud and Prozac.)
I wake up easily, feeling fresh and ready for the day, instead of struggling to waken and feeling groggy till mid morning in wintertime.
It can also be set to simulate sunset, dimming gradually and turning itself off - I've yet to see it go off, as I fall asleep so readily, and so gently.