If sleep is a problem, you know as well as I do that at some point, the caffeine has to go. Trouble is that caffeine, even in small doses, blocks sleep neurotransmitters, the calming chemicals your body makes to make you sleepy. Caffeine is a powerful stimulant with effects that can last up to 7 hours. And for people who have liver problems, or who are taking oral contraceptives or other medications, caffeine’s effects can last even longer! It interferes with the body’s natural regulatory rhythms and chronic use of it can leave one perpetually out of balance — and regularly struggling for sleep.