@Marco.
I'm a non smoker and I just applied a 15mg nicotine patch a couple of hours ago. I experimented with nicotine two years ago (see
this post and
this other one for the result). The mental clarity I had that time was pristine - total cognitive recovery, if short lived - and it happened about 10 - 12 hours after applying the patch. Unfortunately when I woke up the following day I was back to 'normal'. I tried a smaller dose of nicotine shortly after the first time with no effect but I couldn't face making myself so sick again so I never repeated the original dose.
Because of the 10 hour delay I was working on the assumption that the effect may have been due to a metabolite of nicotine but having seen your OP, I've been trying to pluck up the courage for the last month to try again.
I'm going to keep the patch on for as long as I can stomach it, until bedtime if I can, hopefully sleep through the worst of it (or have some
hideous dreams) and will report back in the morning.