hi, ruggles,
i'm one of the lucky ones who vomitted once and then never again during my pregnancy, so I can't help u.
But fm what I read, morning sickness can happen anytime of the day. and will usually stop after the 1st trimester, usually at 4mos.
also, old folks say that the more nausea, better 'cos that means more hormones and therefore the pregnancy is more stable. dunno true or not, har.
anyway, if u're worried, call ur gynae! i call me gynae all the time - gotta make my money's worth. hee!