One of the reasons why the short daylight hours are a problem is that it messes up the melatonin cycle, which in turn derails your sleep cycle. There's too much melatonin in your circulation and your brain downregulates its sensitivity to it. As a result, your brain will not get the usual signal at bedtime to fall asleep.
That's also what I have read, luckily I don't personally have issues with sleeping.. well not serious ones. It takes me 15 minutes to fall asleep instead of the 5 minutes, but I think I can manage that.
The high intensity lights should also help with the issue with melatonin cycle, at least with most people.