"Only some people are affected by caffeine before bed."
Breus is always surprised at the number of people who tell him that they can have a cup of coffee before bed with no negative effects. "Caffeine is a stimulant that has been proven to affect everyone," says Breus. "I know that if I measured their brain waves with an EEG, we'd see an increase in mental activity that could disrupt sleep." Breus says that most people who make this claim are probably so exhausted and sleep-deprived that they're still able to fall asleep despite the extra stimulation. But if they skipped their evening mug, they'd most likely have a calmer brain and a more restful night.