"From others…Splitting the dose seems to keep the pain down, but that might actually reduce the prompts to the adrenals to get back in the business of producing cortisol."
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The prompts to the adrenals can be restored by taking the entire dose is the morning when your dose is 10 mg or less. At doses greater than 10 mg, it probably doesn't matter.

I only split my dose when the overriding 3 a.m pain was very severe. I absolutely had to split my dose if I expected to sleep the entire night and be ready for work at 7 a.m. After I retired and tapered down to 10 mg, it didn't seem like I needed to split my dose anymore.

At doses less than 10 mg is when the adrenals need to get going again. Getting back in the business of producing cortisol again is a good way to say it. If the adrenals don't go back to work, I wasn't working which is probably why I retired ... no energy for work!

I think it might depend on the person and the amount of the evening dose. I read that no more than 1/3 of the daily dose should be taken as a second dose, and only if morning pain wasn't managed with a single morning dose.

From my first and only flare so far at 6.5mg - 6mg, I know that 7mg was my lowest effective dose. So on this tapering, from 8mg on I've reduced my early evening split dose of 2mg down by .5mg for each of the last two reductions instead of lowering the morning dose. I wanted to experiment with reducing the second dose before getting to 7mg again. Been a week on 7mg with a 6mg morning and 1mg early evening split and so far so good. It wasn't enough of an evening dose to control morning pain earlier but it's good now.