@Kolyo,
I used to be a lab tech (1st career) and practically fainted myself at the beginning of taking real patients' blood. I got over it, naturally, and was soon pretty good at it, and even at the start, I wasn't afraid of blood itself, or needles, just fear of screwing up and hurting the patient. I remember being told to watch out for the unexpected - the strongest looking guys might be the ones to faint. Smelling salts always at hand, at least at our lab. Later, I trained others to take blood from me.. sometimes owwie..
A lot of people (I read) skip breakfast and there are a lot pros and cons, probably mostly cons, expressed online. Back in my hectic days, I always had some kind of breakfast, which was a problem since I always had to be up early and liked to or had to stay up late. Kolyo, you might mention that to your doctor (not my business). I now am relaxed in the morning and have coffee(s) first, may not eat for a few hours. Never feel faint in the a.m. This may be related to people having differing relations with glucose.