That's biorhythm, it has nothing to do with food intake. You will have a tendency to fall asleep around 2 pm, more or less, everyday, based on your internal clock.
I try to take 10-15,000 IU (of D3 in gel cap) two to three times a week. Yes, it really works in that my blood testing showed the difference. I have seen no side effects, but then I was really, really deficient.
One side benefit: No more symptoms associated with Seasonal Affective Disorder.
