Hello! Well, sir the information that you have given is not sufficient to guide you through what to do next, like your son s age, number of years of illness, duration of untreated period, what other medications he was put on and how well has he responded to the medications and for how long has he been having difficulty in sleeping.,etc. with the available information I think the sleeplessness and disturbed sleep could be because of a couple of factors, the illness( bipolar disorder) itself or if there was a change in medication or dosage of medication in the past few days following which he has disturbed sleep, daytime sleeping. Since he is on lithium its important not to take the vomiting lightly, that could be one of the early sign of lithium toxicity, the reason why he is waking up several times (is it because of increased frequency of urination?).The most important thing to do right away is to do a serum lithium level and consult your psychiatrist at the earliest, rule out this possibility first and then we can look for other possible causes.