You can’t sleep
Insomnia is a telltale sign of too much caffeine. Even if you swear coffee doesn’t have any effect on you, this tasty drink can still wreak havoc on your sleep cycle. According to Mayo Clinic, coffee can stay in your system for as long as 14 hours, increase the number of times you wake up during the night and decrease overall time asleep. To solve this problem, try to drink that last cup of coffee no later than noon.