Interrupting sleep and causing an afternoon slump are two reasons to lay off the coffee, Entrepreneur tells its readers.

Your afternoon slump may just be you coming off your caffeinated high. Research from Johns Hopkins Medical School suggests that energy jolt you get from your morning cup of coffee are the result of temporarily reversing symptoms of caffeine withdrawal. In fact, the researchers found caffeine-related performance improvements were non-existent without caffeine withdrawal, suggesting that cognitive performance decreases and mood worsens throughout the day when caffeine leaves the body and the only way to get back to feeling “normal” is to drink more caffeine.