to much caffeine will cause "overdose" symptoms. Ever since I started drinking coffee "alot" I have noticed these symptoms an hour or two after taking Carbamazepine (generic tegretol). My doctor confirmed my suspicions. My symptoms usually are: hard to concentrate and very lazy eyes. I find it very difficult to keep my eyes open. I did overdose on medication once. I forgot and took double the dose. I did have the tunnel vision that your speaking of. One thing I've figured out over the years is that it is VERY important that you don't forget to take any medicine. Take it as close to the correct time of day every day. I keep a pill holder on my key chain just incase I forget to take it in the morning. If you miss a dose tuesday morning it may not affect you until wednesday night. It's important to keep the right level of medication in your body all the time. If you don't you run a real risk of having a seizure.
I'm not to sure about the benefits of MJ and seizures. I'm still trying to figure that out. I will say I'm a recreatational smoker. I smoke once a day right before I go to bed almost every day. I haven't had a seizure in years. I do however still have aura's from time to time. That's probably because I don't always take my medicine on time everytime. For me, I know for a fact I will continue to have seizures if I stopped taking my prescribed medication. I do think smoking MJ daily may have something to do with me not having a grand mal seizure in a very long time. I would have to stop smoking weed to confirm that. Not sure when that's gonna happen.