How long do the effects of food last?

I've not yet found a satisfactory answer to this question (if indeed there is one!).

I'm wondering how the food we consume in the day time affects the quality of dreaming at night. In the sticky thread it says that a lot of the vitamins 'stay in the system for a long time', but does anyone know roughly how long and when their effects become negligible? Looking at all the different vitamins that aid dreaming it seems that eggs tick a lot of boxes, but I tend to eat eggs in the morning or afternoon and would prefer not to be guzzling eggs before going to bed :lol:

Does having a general diet high in the recommended vitamins still bring positive effects?