One great way (for me) to get back in the rhythm of things is to get away to a different environment a little closer to nature... even a bed-and-breakfast in the country, and even better, camping at a nice mild spot some nice time of the year. Actually being out in the environment where your activities are influenced by being outside helps you sleep like a baby, I find.

Up north, the same goes for skiing!

Nothing I've done at home (melatonin, changing bedtimes etc.) has had as much definite impact on my adjusting to day-night cycles as simply going camping for a single overnight trip... it's been kind of amazing.