Re: Acids and sleepiness
Well, the acids themselves are very unlikely to have any psychoactive effect, but many other byproducts of funky yeasts could.
The aldehydes, of which there are many in beer (especially funky beer,) are of particular interest.
For instance, acetaldehyde, when digested by those who regularly consume alcohol, can form compounds with neurotransmitters called Tetrahydroisoquinolines (THIQs) that have opiate like effects.
Regular consumption of alcohol is necessary to cause the liver and brain to create this reaction, but it's quite possible for folks like us (I'm assuming you drink regularly.)
There are a whole load of other aldehydes and esters (read: solvents) that could have effects of their own and/or alter the alcohol's psychoactivity.
Regarding the type of beer....the funkier the beer, the more strange byproducts the yeasts produce.