Hi Yes Nebistar and novastat are both known to cause insomnia, nightmares, though these are rare side effects seen with these drugs. I suggest you discuss this with your treating physician as there are plenty of alternate options in both the category of drugs. Nebistar is nebivolol, a beta blocker. Some of the drugs in this category are known to cause nightmares, difficulty in sleep and in my opinion I would consider changing the drug class to some other category like ACE inhibitors or Angiotensin receptor blockers. These are alternate drug class of drug for the same condition and are very less likely to cause disturbances in your sleep. Novastat can sometimes cause difficulty in sleeping though nightmares are uncommon. You may discuss this with your physician in your next visit. Hope I answered your queries. We can know for sure which of these is causing the problem by stopping the drug to see how the problem resolves or not. But this should be done only under the guidance of your treating physician.