SAD the mystery?

I have been suffering from depression for a very long time but I first
noticed it wenn I came oversees to study in Germany.It was on a winter when I landed my foot on German soil und since that day life siezed to exist for me.
From a highly intelligent man I become sick all time, weak and unable to read
as I had no energy to read before talking of understanding. I could only sleep for very long hours but the sleep does not bring any recovery. Life became a horror trip.I tried antidepressiv drugs but It never worked and the side effects worsen the whole situation. I got no better with antidepressiv drugs and with no drugs too I had no energy to funktion.
After many years now it is clear I have SAD.
I already suspected Sad some fours ago and but a light box at that time but it did not work at that time because I was on antidepressivs and the light box was then very uncomfortable or even increased the side effects at the time.
My depression hat just one but very serious symptom of lack of Energy.Every other thing was okay.I was a happy person,optimistic,never giving up but unfortunately never making a success because of lack of energy. I always had the whole year no energy, always feeling weak.
But I keep on researching and reading wanting to know what is wrong with and at the end with no success I came back to light box again.
Since seven days I am on light therapie and it works und seems to have an influence on the serotonin production in my body.
My question is: does light therapy boost only the serotonin production?
What of the norepinephrines? I ask because it seems my body lacks but norepinephrines.
I must say that I am happy for the little success of the 7 days therapy with light box. For example I have become more optimistic. Even after 2 days the problem I always had before not being able to make a decission was gone. For example my long time girlfiend had been treating me badly probably because life was seeming hard for me. So she went further threatening to break the relationship but I was not wanting it because we have a small child and I want him to grow wit me. However I must say my girlfriend became depressed after she gave birth. I tried to make the point clear to her that she was depressed but she refused. Even she wanted this child in other to bind me to her but when the depression came she forget all that and she developed other eyes so to say and did not see me again as her prince.
Any how 4 weeks ago she ended the relationship and I was feeling a little sad only because of my son that I donot see everyday anymore as I used to do. He is just 2 years but resists the separation vehemently so that when I visit them and want to leave,he will run very fast to me and seized my winter coat and run with it to the sleeping room. Other times he will run to his Mum and point to me crying meaning she should prevent me from leaving but my girlfriend shows no feeling and understand for my son´s needs.
Depression is a terrible thing. It breaks down relationship and families.
Lets us go back to the light box. So even after 2 days use my sitiuation improved so that could take decissions quickly and clealy and I immediatly saw that I do not match to my girlfriend and the interest on her disappeared immediatly except for my son that the love instead increased.
I hope this letter of mein fromGermany did inspire you to look forward with hopes as I do.