For those considering upping the dose at night and reducing the dose in the am to reduce daytime tiredness......The half life ( or time Carbamazapine remains in your bloodstream) is long so that this methodology won't make much difference. You can of course get your carbamazepine levels checked by your Dr to make sure they are at a reasonable level. (Although this test is usually reserved for those requiring the drug for epilepsy/bipolar disorders).