This one is personal. These are the four I keep for myself, and the four I reach for most often when a woman tells me she is running on empty.
Magnesium, because it is used in hundreds of processes in the body and most of us are getting nowhere near enough. It is the one people notice first, in their sleep and in their shoulders.
A B-complex, because these are the vitamins your body spends fastest when you are stressed, and they are what turn food into usable energy.
Ashwagandha, a plant that has been used for a very long time to help the body cope with being under pressure.
And omega-3, because the fats that switch off inflammation are the ones almost nobody is eating enough of, and tired and achy usually travel together.
None of this replaces sleep, and I am not going to pretend otherwise. But if you are doing everything on four hours and a cup of coffee, this is the floor underneath you while you sort the rest out.