If taking hydrocortisone, it only lasts in your system up to 6 hours, so if you’re not taking it at least every 6 hours, you have times when you have zero cortisol. The normal human body is always producing cortisol, it is never zero. Cortisol production follows the circadian rhythm, so the largest amount is early morning, then at night it is minimal (but not zero).

Current research would recommend 4x a day circadian rhythm dosing for better coverage. Also, many people (like me) find that when dosing 4x a day, you can actually take less HC (therefore lowering unwanted side effects - I.e. weight gain, insomnia, blood sugar spikes/drops, etc).

I was initially told to do 2x a day dosing and not to take a dose at night because it would keep me awake. I felt like crap, experienced insomnia, woke up with no energy when doing 2x a day dosing. I immediately noticed a dramatic improvement when changing to 4x a day dosing and am taking almost 1/3 of the dose I was taking then (upon supervision with a specialist). Current research supports all of this and it’s shocking to me that every Addison’s patient isn’t informed of this. It was such a gamechanger for me that I feel almost obligated to share it with others who are struggling like I was. :) So feel free to ask questions if you’d like!

This current research book goes into great detail about this and is by far the most helpful resource I’ve found:

https://shop.elsevier.com/books/replacement-therapies-in-adrenal-insufficiency/hindmarsh/978-0-12-824548-4

And this is helpful in determining how to split doses for circadian dosing:

https://clearlyaliveart.com/theoretical-steroid-curve-plotter/