Caffeine in brewed Pu-Erh tea

Clever people,

Yesterday I found out that the halving time for caffeine is about 8 hours.

I have a feeling that caffeine affects my sleep (in a negative way).

I’ve tried to find out how much caffeine an average Pu-Erh (shenG) contains – if, for example, the amount from 10g with 10 infusions.

I’d like to hear your thoughts & would appreciate links to sources with measurements of caffeine levels.

Most data I can find are general charts showing the caffeine contents for different tea types (green, black, Pu-Erh, etc.).

Huge thanks in advance,

Kasper