SAD as it is often shortened to can affect anyone. It is unsurprisingly more common in higher latitudes, Norway, Sweden, Finland etc. having particularly high incidences of it.
What can one do to reduce the risk or severity of this disease? To start with it is worth looking at what indigenous peoples did in the past during the high risk months. During the long nights, they would engage in a lot of singing but also other creative things such as carving etc. Did changing to a more introspective lifestyle rather than trying to carry on as normal help? I don’t know for certain but I suspect it did. My message would be don’t give yourself a hard time if your motivation to do things is reduced!
Other things that evidence shows help some is taking extra vitamin D. Normally this is synthesised in the body using sunlight. Get out into the light for a couple of hours around mid day. The evidence is that apart from the two hours around midday the light isn’t strong enough to make a difference.
Get a special light box or light which will give you some of what you are missing. Some might feel that this is denying the body it’s natural rhythm but it is worth remembering that humans originally came from tropical regions where there is not the same seasonal variation in light levels.
And finally there is evidence that massage can help, particularly if combined with oils like Bergamot, Frankincense and others that are good for depression. As well as the scientific evidence, it makes sense that if you do something really nice for yourself it can make you feel better!