yea, i've found that when i do it repeatedly for a couple months, the slowness, bad memmory,lazyness, not-giving-a-shit-ness, and doing bad in school get worse. like for instance, for the past 2 months ive been smoking at least once on the weekend(usually 2 or 3 times) and at least once during the school week. it really is effecting my grades. but then again, i dont give a shit