do you put the main lights on at home when its Dark?
forget SAD lights for the winter , Who makes sure their home is adequately lit? when they are at home ?
I should imagine when youv'e had a sh!te day at work, you've got soaked by the rain and your freezing and feeling depressed , just getting home and going into your house and putting no light on or a small table light, or a room with a dim light bulb or not enough bright light bulb to light the room not only would it put a strain on your eyes whilst your watching TV or computer in a dimly lit room it most probably makes you feel even more depressed even if you dont realise it, even though 'cosy' it may be!
Same when you wake up on these cold dark mornings, forget spending out on these expensive SAD lights from chemists (most of them are just a simple box with a daylight tube in it - you can get an ordinary daylight cfl bulb from hardware store for about 4euro but SAD lights from chemists can cost around 80euro or more!) all you need to do is turn on a main bright light in your rooms at home in the mornings and the evenings when its dark outside.
Try it, I bet it works - when its morning put your lights on in the house (good bright lights) I bet you will start to feel better! and less depressed!
I am no doctor or experienced but its a well known fact that your body system gets tired and sleepy in the dark , its getting ready for sleep mode, and your body wakes up when its light, it indicates to you that you need to wake up - so if you get up on a dark pitch black winters morning and all you do is put on a dim bedside lamp and you cannot seem to properly feel awake in the mornings try putting on your bright main room lights as you are waking up - see if that makes you wake up quicker and feel better.
Its the same for businesses without big enough windows or insufficient lighting if for some reasons your bosses turn of the lights to save electricity or whatever reason and the staff feel tired all the time it could be because there is not enough daylight , time for the tiredness and depression to kick in, this might indicate why some people are depressed in some jobs than others and by just brightening up the office or wherever your working and turning on sufficient lighting it might just lighten up the mood of the workers and a happier workforce will be more efficient and maybe less time off work.