on my days off if i have nothing to do i will happily just lounge on the sofa all day smoking shitloads thats when by late afternoon i useally have a few ZZZZZs.i find if i don't keep active i sometimes do feel tired, but don't think it has anything to do with tollerance, as i've been smoking 25 yrs, smoke 24/7 and have a high tollerance, i think it is the lazy stoner syndrome with me.