I'm a definite fan of getting mid-day sun, but my understanding is while it'll help maintain sleep rhythm, it won't correct it if it's already out of whack.
For that, I'd suggest getting some sun (or failing that, some light therapy lamp exposure—a special-purpose lamp that puts out a blinding amount of light) first thing when you wake up. Of course, you could optimize further too, like this paper suggests.
I have occasional problems with sleep disruption in the winter months (October to March, 49 degrees latitude). The problem is that natural sunlight simply isn't strong enough to reset your body clock.
When it happens I take a melatonin at night, and it seems to reset my sleep cycle and gives me a really good night's sleep. I don't normally take it more than once a week at most, just in case there are any negative effects. The delayed release tablets seem to work best (Jamieson, I believe it is), as they slowly release the melatonin over a period of 8 hours.
For that, I'd suggest getting some sun (or failing that, some light therapy lamp exposure—a special-purpose lamp that puts out a blinding amount of light) first thing when you wake up. Of course, you could optimize further too, like this paper suggests.
Source is admittedly Wikipedia: http://en.wikipedia.org/wiki/Delayed_sleep_phase_disorder#Ma..., and http://en.wikipedia.org/wiki/File:PRC-Light%2BMel.png in particular.