In the UK I used to get hit by it around January/February time. It took me a few years to twig that I would have an uncharacteristic period of not coping, weepiness and inability to motivate myself. Once I had worked it out I made an effort to book in things to look forward to (as much as possible when pretty much constantly pregnant or breast-feeding!) such as my annual haircut(!!), or a day out somewhere.
The last couple of years I have found myself feeling the same way, I dread the shorter days and cold nights and find that I am unmotivated to read, or do anything creative. However this year I think the fact that I am bored rigid has also contributed. I always tell the kids that only boring people get bored, but I think I have passed my SAHM date. I had planned on 10 years but am now in my 14th, I haven't been successful in finding teaching work here (plenty of RE jobs going in the UK...) and so am feeling a bit aimless. Between 3pm and 9pm I am run ragged with activities so have been making the most of Mon-Wed, when I am child-free between 9 and 3, to get out of the house, walk the dog, get warmed up, have a coffee, attempt some writing and see the sea. It has definitely helped to keep me sane this Winter. We have also enjoyed LiveSites Winter Heat again, and I'm sure having 3 birthdays within 5 weeks helps keep me focussed on fun times.
The kids are now at home for 2 weeks so no 'Me time' but plenty of action/drama/fun/frolics will, no doubt, be had. And plenty of sleepless nights and lie-ins as I stay up to watch as much of Wimbledon as possible! Then we will be heading into Spring and hopefully some exciting plans.
I would love to know if any of you suffer too and how you deal with it. In an ideal world, I would take to my bed with a cosy duvet for a couple of months!