Every year we notice two weeks that seem to affect a number of folks who have had seasonal depressions.
The first period is the “End of Summer” – a foreshadowing of the coming fall that happens in late August or early September (depending on the weather, we guess).
The second period is the “Beginning of Winter” – which usually takes place around Halloween and is definitely related to weather (often timed to coincide with the first storm of the winter season here in the San Francisco Bay Area.
We have just entered the “End of Summer” period in the bay area.
This week a number of people have been complaining of suddenly feeling tired despite sleeping longer than usual. It also happens that it has been a particularly foggy week (and hence a particularly dark one).
The tiredness is not going to respond to sleep, but it is hard to convince oneself of that when it is early in the morning and cold and dark outside. In fact, sleeping in is likely to make it worse.
The thing to do now is to prepare for the winter. That means making sure that you have set up therapy lights that you can use to maintain strong circadian rhythms even after the sun is no longer around to help set them.
Or you can go into a modified form of hibernation, which is what our ancestors would have done in the winter in northern locations.
However, we are going to assume that your boss is not going to be OK with having you disappear from work for a few months.
Our personal favorite seasonal affective disorder light is from BlueMax LIghting. Their 72 watt floor and desk lamps are perhaps not the most attractive lamps in the world, but they are also not obviously therapeutic lights, 
meaning you can use them at work and home just as you would any other light. And since they are full spectrum bright lights your vision will be better if you use them during the day.
But there are a number of alternatives (see below). Blue lights take advantage of the fact that the part of the light spectrum that is most effective at “setting” your body clocks is in the blue spectrum. They work pretty well. Although people definitely feel a bit strange at first being bathed in very bright blue light. Don’t buy one of the “dawn” devices for this purpose, they may make great alarm clocks but they are not going to get you the kind of bright light exposure you need.
For most of the people we see we suggest 30 to 45 minutes a day of bright light (usually the light has to be a foot and a half from your eyes and has to be visible in both eyes, although you don’t have to look at it directly) a day. Set the light up so that you can read or reply to emails, or post to your blog :-).