Depending on how much you smoke during the day, Tobacco causes what we used to call in school "head spins". It feels very similar to SP, very very similar. Now I'm not one to like to take away someone's placebo effect, but I've found it's better because then we can find what REALLY works. Basically I think you just THINK that you're having SP but it's really just "head spins" which everyone gets from smoking Tobacco if they aren't regular smokers.

These head spins can consume your whole body if you focus on them, I remember when I started smoking and I went down the street to this grassy field with long long grass and I smoked the entire 16mg nicotine cigarette for the first time. I got massive numbness all over my body and I just fell back into the grass and was 'floating'. Just tingly numbness everywhere.

(god, now I remember why I started smoking! haha. It was so good)

I believe this is because Tobacco is a stimulant, plus it slows down your circulation. Which is why it feels very similar to cutting of the circulation to a leg or something when you're sitting down for too long. Except all over your body. If you are focusing on this though, it would be like a meditation, which in itself, as SKA said could help to LD.

I would suggest trying to prolong this feeling when you smoke, eventually you will be able to get it without smoking at all, if you want to.

Also, although this is not really known widely, Tobacco contains Muscarine, which is also in those Amanita Muscaria mushrooms (red and white spotted ones from fairy tales), which have been documented to induce LD's. So maybe that's what's doing it?
Maybe Winston Light's contain more Muscarine for some reason?