Short post this - I just wanted to share something that I've noticed over the past three months that gets very little attention in the office workspace press, which is currently obsessing over whether to sit or stand whilst at work.
I've started getting in to the office earlier, and I have an east-facing window next to my desk. When I get in to the office, the first thing I used to do was turn on the lights. Now I don't and I sit at my desk for at least an hour with just the natural daylight coming in. And I can't tell you how jarring it is when someone from the 'west-side' (i.e. dark in the morning) comes in and turns the lights on.
Daylight is far easier on the eyes, and more relaxing and comfortable than standard office strip lights - and it's surprising how dark it can be outside whilst continuing to work. Give it a try.