I can't say I noticed a change in mood when taking D3. However fish oil undeniably reduces dryness in the EYES, with and without contact lenses. They do sell in pharmacy supplements for eye health, I think targeted at older people, and the dosage of EPA /DHA is very low. I didn't try those so I can't say how much is needed. I took eg. Life Extension 700/500 epa/dha and for me the effect was 100% reproducible. On a da…
I didn't noticed a lot of changes with 2000 IU but at 5000 IU the effect on mood is dramatic and quite noticeable. Being liposoluble the effect has quite a latency over several days.
It's basically the "summer vacation" feeling.
(Be carefult to take pure D3 not something mixed with calcium though: effective dosage of vit D. would bring into calcium overdosage.)