Interesting thoughts...
It's not dull and grey here - I live for the bright crisp winter days - today was one such - well not quite winter yet. Beautiful sunshine and light, and amazing colours of the leaves. Wild branches waving in the wind. Also lucky to live not far from the sea - 20 mins drive so the waves and storms are fantastic - bound to make you feel good. I love the summer too and get excited when the year turns, (winter solstice - sorry Taz!) but then I like all the turns of the seasons. To me there is something about each time of year that appeals so you just have to look for it. OK I am really tired a lot of the time now but it doesn't mean I want to hibernate!
Honeybun yes you live by the sea - but I think it's probably to do with your situation more than the time of year - I think the greyness and cold can make one less able to deal with life's problems. Also you mention the low light - I've just looked it up and for those in Scotland your day in Glasgow is nearly an hour shorter than mine near Exeter! it;s also much colder! No wonder you want to hibernate!
Glasgow sunrise: 8.33
sunset 3.44
Exeter sunrise 8.02
sunset 4.09
Hurdity x