What I was sadly not aware of until recently is that you can get daylight versions of these!
(Note: this is not "cool" or "blue-ish" light, it is white light. Neutral. It can seem cool because over decades we have gotten used to the strongly orange-y light from normal bulbs (se photo below). But this is the light spectrum like it comes from the sun, and it is what our eyes have evolved to make use of.)
Especially here in Northern UK, it's easy to get into dark moods in the wintertime, because it simply is so dark outside, and the body/eyes need daylight. The night lasts like 16 hours or more, and most of the days are dull and dark too.
I just got several of these daylight bulbs, and to my surprise, they make a difference right from the start. I feel cheerier and more energetic. If this is a lasting effect, it's a major thing. It seems to me now, already, that the old orange-y bulbs is kind of "dying light" in comparison to this energising daylight.
When I got my first "100 Watt-equivalent" energy-saving bulb years ago, it didn't seem to me to live up to the promise of that much light. So I bought 100w-equivalent this time too (25W). And they are certainly that, this time! Bright. These may even be too bright for some uses, we will see as I get used to it.
Anyway in general, I think some people will have to take a couple of weeks to get used to having the daylight spectrum indoors.
I really think they should be known about much more widely. Get a trial one today. :-)
Oh, and another thing: if you are reading ebooks on an e-reader without either backlight or frontlight, just the basic grey-ish e-ink screen, you may find that the full-spectrum light makes reading easier.
Oh, if you doubt there is much difference, look at this! :
...you might want to add, to the attention of northerners like us, is that as soon as you start heating the house, from fall all through winter, the energy used to light your days is essentially free, since it will end up as heat anyway. So, whether you spend the money on "invisible" heat or light up your days and chase depression at the same time, the cost doesn't change much.
Of course there's always the wear on the bulbs and that's where the latest generation of ultra-long-lasting bulbs really shine - many just won't die! And the savings on doctor visits, pills, cold medicine and whatnots offset the cost of the bulbs many times.
(Yes, In all the years I've used energy-saving "bulbs", I've only had one single one die on me.)
There are recommendations of the newer LED bulbs, I'll look into those also.
Update 31 Dec:
Just thought I'd let you know I received the daylight bulbs a few days ago and you're right, they have already made a huge difference, it's like a springtime afternoon outside in here, most pleasing!
And they've added a kind of cool clarity to the atmosphere, first of all was a little disconcerting though have got used to that now :)